Download Reflecting `Popular Culture`: The Introduction, Diffusion, and

ANNALS OF SCIENCE, 61 (2004), 407–452
Reflecting ‘Popular Culture’: The Introduction, Diffusion,
and Construction of the Reflecting Telescope in the
Netherlands
HUIB J. ZUIDERVAART
Museum Boerhaave, PO Box 11 280, 2301 EG Leiden,
The Netherlands. Email: [email protected]
Received 17 April 2002; In final form 31 October 2002
Summary
The eighteenth century was an era in which science came to play a major role in
the cultural ideal of the city elite. The phenomenon of the ‘gentleman-scientist’
arose: a layman without a scientific education who for a variety of often socially
desirable reasons devoted himself to scientific endeavours. Scientific instruments
were the tools for this interest. This article describes the introduction, diffusion,
and construction in the Netherlands of one of the most prominent eighteenthcentury instruments: the reflecting telescope. The reception of this instrument
casts new light on the usually almost invisible network of gentleman-scientists
and instrument-makers in this region. The specific economic and political factors
of the Netherlands led to a totally different development of this instrument compared with the ‘motherland’ England. Whereas in Great Britain the reflecting
telescope was a great success well into the nineteenth century, in the Netherlands
it became a symbol of technical inability and stagnation.
Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2. Development of the reflecting telescope: from clever concept to
commercial product . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Introduction into the northern Netherlands . . . . . . . . . . . . . . . . .
3.1. Fahrenheit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2. English import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3. The Van Musschenbroek Workshop . . . . . . . . . . . . . . . . . . .
4. Amsterdam ‘virtuosi’ and their interest in optics . . . . . . . . . . . . . . .
4.1. Merchant-scientists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2. The philosophical component of optics . . . . . . . . . . . . . . . . . .
4.3. Jacobus van de Wall and his ‘great telescope’ . . . . . . . . . . . . . .
5. The diffusion of technical skills to Friesland? . . . . . . . . . . . . . . . . .
5.1 Franeker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 The Amsterdam connection . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Frans Hemsterhuis and Petrus Camper. . . . . . . . . . . . . . . . . . .
5.4 Leeuwarden and Groningen: the influence of the Stadholder’s court . .
6. Dutch reactions to the achromatic telescope . . . . . . . . . . . . . . . . . .
6.1 Bley and Van Deijl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2 Van Musschenbroek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3 Van de Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4 Van der Bildt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.5 Industrial espionage ordered by Frans Hemsterhuis . . . . . . . . . .
Annals of Science ISSN 0003-3790 print/ISSN 1464-505X online # 2004 Taylor & Francis Ltd
http://www.tandf.co.uk/journals
DOI: 10.1080/00033790410001654890
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7. The end of the Dutch production of reflecting telescopes .
7.1 Van de Wall’s telescope at the Leiden Observatory . . .
7.2 New technological developments . . . . . . . . . . . . . . .
7.3 Frisian ‘farmer professors’ . . . . . . . . . . . . . . . . . . .
7.4 The fiasco of Roelofs and Rienks . . . . . . . . . . . . . .
7.5 The demise of telescope production in the Netherlands
8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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1. Introduction
On 20 April 1782, the curators of Leiden University received an unusual
letter from Amsterdam. The executors of the estate of the merchant Jacobus van de
Wall offered a remarkably large reflecting telescope, complete with astronomical
observatory and other associated objects, free of charge, on the condition that it
was collected at the University’s cost from the home of the deceased in Amsterdam.1 It
was indeed a remarkable gesture, although at that time, it was not unusual that
private individuals offered scientific instruments to the university.2 But a complete
astronomical observatory? No, there was no precedent for such a gift in the
Netherlands. Even more noteworthy was the fact that the deceased had designed
the instrument personally, and even the mirrors were polished with Van de Wall’s
own hands. Like other leading telescope-makers of the period, Van de Wall had not
enjoyed any formal education in either astronomy or the making of scientific
instruments. Neither was there any relationship with the University of Leiden.
Nevertheless, the curators of Leiden University did not hesitate to accept the
gift. The information obtained indicated that the telescope in question was a
‘splendid piece’ of a much better quality than the telescopes available at that time in
the University observatory.3 Besides, at the time, it was the largest telescope present
in the Netherlands.
This article will follow the reflecting telescope from its introduction in the
Netherlands, around 1730, to its demise in the nineteenth century. In this story,
the role of the konstenaar (‘artisan’) will be emphasized. As ‘invisible technicians’,
the role of these instrument-makers is all too often overlooked.4 Recently, Roberts
quite correctly wrote about this:
1
Meeting board of curators of the Leiden University, 15 April 1782 [Univ. Libr. Leiden, Archive
Curators (AC), I-35, fol. 18vs–19vs; 24; AC-I-60].
2
Other gifts of astronomical instruments to the Leiden University were (1) a Copernican sphere,
called ‘The Leidse Sphaera’, given in 1710 by the Rotterdam family Schepers [see E. Dekker, The Leiden
Sphere. An Exceptional Seventeenth-Century Planetarium (Leiden, Museum Boerhaave, 1986)]; (2)
various astronomical instruments, in 1743 by the late Samuel J. Garama from The Hague (AC-I-33, fol.
11); (3) an astronomical clock, in 1791 by the late Willem Snellen, burgomaster of Dordrecht [see R. H.
van Gent and J. H. Leopold, The Time-Keepers of Leiden Observatory (Leiden, Museum Boerhaave,
1992), 18–19]. For other gifts of scientific instrument to the Leiden University, see P. de Clercq, ‘In de
schaduw van ‘s Gravesande. Het Leids Physisch Kabinet in de tweede helft van de 18e eeuw’, Tijdschrift
voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, 10 (1987), 149–73,
esp. 160–1.
3
Concerning the equipment of the Leiden Observatory, the French astronomer, Lalande, reported in
1774 that he had not seen any instrument there worthy of mention. J. de Lalande, Bibliographie
Astronomique (Paris, 1803), 802, 856, 872; G. van Herk [et al.], De Leidse sterrewacht. Vier eeuwen wacht
bij dag en nacht (Zwolle, 1983), 24.
4
The expression ‘invisible technicians’ is coined by S. Shapin, A Social History of Truth. Civility and
Science in Seventeenth-Century England (Chicago/London, 1994), 355–407. See also N. C. Russell, E. M.
Tansey, and P. V. Lear, ‘Missing links in the history and practice of science: teams, technicians and
technical work’, History of Science, 38 (2000), 237–41. The situation in the Netherlands is outlined by
P. de Clercq, ‘The instruments of Science: the Market and the Makers’, in A History of Science in The
Netherlands: Survey, Themes, and Reference, edited by K. van Berkel, A. van Helden, and L. Palm
The Reflecting Telescope in the Netherlands
409
Much work has yet to be done before we have a good historical understanding of why some technicians languished in obscurity (historical or
otherwise) while others managed to transcend institutional constraints and
prejudices. Quite apart from the obvious attribute of technical skill, a wellworked-out explanation would have to examine the role of commercial skill
alongside questions of status, patronage, and corporate identity, all of which
varied with local economic and sociocultural conditions.5
2. Development of the reflecting telescope: from clever concept to commercial
product
The invention of the reflecting telescope is generally attributed to Isaac Newton,
who built this instrument with his own hands in 1668: although, in the first half of
the seventeenth century scholars had already considered that the desired magnifying
effect in a telescope could in theory be achieved with a concave mirror, almost
nobody had actually tried to construct such a telescope.6 The loss of light due to
reflection in such a telescope was too great compared with the transmission through
the glass. Furthermore, there was no theoretical necessity for such an effort. Why
make an effort to achieve something that could already be done in another way?
Moreover, the construction of a working reflecting telescope is far more difficult
than it might appear at first sight.
After the invention of the ‘Dutch telescope’ in about 1608, the lens-based
telescope was gradually perfected during the course of the seventeenth century.7
One of the remaining problems was the diffraction blur as a consequence of
spherical and chromatic aberration. Newton realized that each colour is refracted
differently in glass. He therefore assumed that the colour shift in lenses could not be
solved in principle. So, at that time, Newton had a theoretical motivation for
constructing a reflecting telescope. Shortly before, in 1663, James Gregory had
(Leyden, 1999), 311–31. The difference between artisans (Dutch: ‘konstenaars’) and theoretical scientists
is briefly discussed by J. F. Hennert, ‘Eerste verhandeling over de acromatique of Dollondsche
verrekykers, bevattende de algemeene eigenschappen dier werktuigen’, Verhandelingen van het Bataafsch
Genootschap der Proefondervindelijke Wysbegeerte te Rotterdam, 1 (1774), 272–432, esp. 383.
5
L. Roberts, ‘Science Becomes Electric. Dutch Interaction With the Electrical Machine During the
Eighteenth Century’, Isis, an International Review devoted to the History of Science and its Cultural
Influences. (1999), 680–714, esp. 687.
6
The first recorded attempt to construct a reflecting telescope was in 1616 by Zucchi. See Riekher,
Fernrohre und ihre Meister (1990), 88–94 and R.N. Wilson, Reflecting Telescope Optics I. Basic Design
Theory and its Historical Development (Berlin/Heidelberg, 1996), 1–14. For these early attempts, see also
Piero Ariotti, ‘Bonaventura Cavalieri, Marin Mersenne, and the Reflecting Telescope’, Isis, an
International Review devoted to the History of Science and its Cultural Infulences. 66 (1975), 303–21 and
Anthony Turner, ‘The Pre-History, Origins and Development of the Reflecting Telescope’, Bullettino del
centro internazionale di storia delo spazio del tempo, no. 3–4 (1984), 11–22, reprinted in Of Time and
Measurement. Studies in the History of Horology and Fine Technology (Aldershot, 1993), art. XXI. The
suggestion that the Englishman Leonard Digges made a operational reflecting telescope in the third
quarter of the sixteenth century seems to be sufficiently refuted by G. L’E. Turner, ‘There was no
Elizabethan Telescope’, Bulletin of the Scientific Instrument Society, No. 37 (1993), 2–10.
7
For the invention of the refracting telescope, see Cornelis de Waard, De uitvinding der verrekijkers.
Eene bijdrage tot de beschavingsgeschiedenis (The Hague, 1906); Albert van Helden, ‘The invention of the
telescope’, American Philosophical Society, Transactions 67, part 4 (1977) and G. L’E. Turner,
‘Animadversions on the origins of the microscope’, in J. D. North and J. J. Roche, The Light of Nature.
Essays in the History and Philosophy of Science Presented to A.C. Crombie (Dordrecht, 1985), 193–207.
For its further development, see A. van Helden ‘The Telescope in the Seventeenth Century’, Isis, 65
(1974), 38–58; H. King, The History of the Telescope (1955; second ed. New York, 1979) and R. Riekher,
Fernrohre und ihre Meister (Berlin, 1957; 2. stark bearbeite Auflage, 1990).
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published a plan for such a telescope. In that design, Gregory had combined a
parabolic concave mirror made of metal with a smaller one, this time elliptical. In
theory, this combination of mirrors gave a focused image in front of the main
mirror. However, the practical construction of the instrument floundered on insurmountable problems.8 Therefore, Newton chose a simpler design. His telescope had
a concave spherical mirror, in combination with a flat mirror.9 By keeping the
primary mirror small in relation to its focal length, the deviation of the necessary
parabolic form was in practice not noticeable.
Newton’s success may be described as exceptional. It is often attributed to his
considerable practical experience, including alchemy experiments.10 In the following
years, only Robert Hooke succeeded in constructing a more or less working example
of a reflecting telescope.11 A French design published in 1672 by Cassegrain also
remained on the drawing table.12 Time would reveal that only a thorough and
lengthy practice in shaping and polishing mirrors would lead to acceptable results.
These, added to the fact that a suitable alloy for the mirror metal could not easily
be found (once polished, the mirrors quickly became tarnished), were the reasons
why for the first 50 years after Newton and Hooke, hardly any reflecting telescopes
were constructed.
In about 1720, the problem was tackled again, this time by John Hadley, who in
1728 would become vice-president of the Royal Society of London. This gentlemanscientist had considerable funds at his disposal. He experimented widely with a
great variety of metal alloys. For a good telescope mirror, the metal needed to be
both dimensionally stable and strongly reflecting. Unfortunately, these two properties were often associated with a polishing problem. The harder the metal, the
greater was the chance of microscopically small holes arising in the surface.
This stimulated the oxidation of the metal, which diminished both the reflective
capacity and the image forming quality.13 It was also difficult to give the metal a
homogenous composition, and so the polishing of the metal surface gave an
unequal effect at different places. Moreover, such problems often only came to light
once the mirror was almost ready. Therefore, it was very important that Hadley
developed a test method with which he was able to establish deviations from the
desired form already during the polishing process of the mirror.14 The development
of the reflecting telescope was, therefore, largely due to the efforts of gentlemanscientists, as only those with an unlimited amount of time, money and patience
8
King (note 7), 71; A. D. C. Simpson, ‘James Gregory and the Reflecting Telescope’, Journal for the
History of astronomy, 23 (1992), 77–92.
9
Newton used a prism instead of a flat mirror in the description of his reflecting telescope given in
Opticks. See I. Newton, Opticks or a Treatise of the Reflections, Refractions, Inflections & Colours of Light
(1704; New York, 1952), 107–11.
10
M. Daumas, Scientific Instruments of the Seventeenth and Eighteenth Centuries and their Makers
(New York, 1972), 167 (translation of Les Instruments Scientifiques aux XVIIe et XVIIIe Siècles) (Paris,
1953).
11
A. D. C. Simpson, ‘Robert Hooke and Practical Optics: Technical Support at a Scientific Frontier’,
in Michael Hunter and Simon Schaffer, Robert Hooke. New Studies (Woolbridge, 1989), 33–62.
12
Cassegrain’s design was published in the Journal des savants in 1672. It was in fact identical to
Gregory’s, in as far as the secondary concave elliptical mirror was replaced by a convex one. Gregory
had also suggested such a variant. Both settings were also drawn by Mersenne in 1636. Cf. Wilson (note
6), 3–4.
13
A. J. Meadows, ‘Observational Defects in Eighteenth-Century British Telescopes’, Annals of
Science, 26 (1970), 305–17. See also R. C. Brooks, ‘Techniques of Eighteenth Century Telescope Makers’,
Bulletin of the Scientific Instrument Society, 69 (2001), 27–30 and 70 (2001), 6–9.
14
Wilson (note 6), 11.
The Reflecting Telescope in the Netherlands
411
at their disposal could eventually obtain the necessary results. The relatively few
professional instrument-makers active at the beginning of the eighteenth century
could not simply permit themselves to undertake such time-consuming activities.15
In 1723, the first ‘Hadleyan’ reflecting telescope was extensively tested by the
Royal Society. With flying colours, the instrument passed a comparison with a
refractor of long focal length made by Huygens.16 Stimulated by this success, in
1726, Hadley and his assistants also succeeded in constructing a reflecting telescope
according to Gregory’s design. Then, Hadley took a remarkable step. To ensure the
commercial production of this telescope, an instrument that had previously been
too difficult to construct, Hadley and his assistants deliberately passed on their
acquired technical knowledge to two professional instrument-makers, namely
Edward Scarlett (À 1743) and George Hearne (À 1741), both working in London.17
In the following decade, these two opticians would become the most important
constructors of reflecting telescopes. Initially, they produced mostly Newtonian
reflectors, yet owing to its ease of use, the Gregorian version of the reflecting
telescope quickly became the favoured model, whereby occasionally a Cassegrain
version was also included in the assortment.18 The Newtonian model was usually
mounted in an octagonal wooden tube, and the Gregorian and Cassegrain models
were mounted in a round brass tube. This difference in design would be maintained
for decades, apparently to emphasize the fact that these telescopes were two
different products. It was maintained that the Newtonian telescope was more
suitable for astronomical observations, and the Gregorian model was intended for
looking at ‘earthly objects’.19 This differentiation led to potentially increased sales,
as the clients often ordered two telescopes instead of one.20
Through Scarlett and Hearne, the know-how with respect to the manufacture of
telescope mirrors spread amongst the British instrument-makers. The most successful of these telescope-makers was James Short. In 1732 Short had started producing reflecting telescopes in Edinburgh (Scotland). Six years later he established
himself in London. In contrast to most of the other instrument-makers, Short only
produced mirrors, and thanks to this specialization, he enjoyed an unequalled fame.
In the English standard work by Robert Smith, A Compleat System of Opticks,
published in 1738, Short was praised as by far the best constructor of reflecting
15
Anthony Turner (note 7), 16, 19.
J. Hadley, ‘An Account of a Catadioptrick Telescope’, Philosophical Transactions, 32 (1723), 303–
12. See also Philosophical Transactions, 32 (1723), 382–6.
17
A ‘Description of how to cast, grind and polish metal mirrors for reflecting telescopes’ written by
Samuel Molyneux and continued by John Hadley was published in Robert Smith, Compleat System of
Opticks (London, 1738). (Dutch edition, Amsterdam, 1753, 511–24).
18
Edward Scarlett (senior) constructed the first Cassegrain model telescope. This type of telescope has
a convex secondary mirror, which is much more difficult to make than a concave mirror. Facts from this
early period have been collected by J. Th. Desaguliers, in ‘Appendix [. .] containing an account of the
reflecting telescope’. Published at the end of the second edition of David Gregory, Elements of Catoptrics
and Dioptrics (London, 17352), 218–88. See also T. H. Court and M. von Rohr, ‘A History of the
Development of the Telescope from about 1675 to 1830 based on Documents in the Court Collection’,
Transactions of the Optical Society, 30 (1928–1929), 218–27.
19
P. van Musschenbroek, Beginsels der Natuurkunde (Second edition; Leiden, 1739), 628–35.
20
This can be concluded from the fact that of the early owners of reflectors in the Netherlands, most
of them were in the possession of both a Newtonian and a Gregorian variant of this type of telescope
(1737: John de Lange, FRS, Amsterdam; around 1738: Petrus van Musschenbroek, FRS, Leiden; 1743:
Natuur- en Sterrekundig Collegie, Haarlem; before 1747: Anthony Bierens, Amsterdam; around 1748:
Pieter Gabry, FRS, The Hague; 1748: Leiden University).
16
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telescopes. Short often combined his mirrors by choosing the best combination
from a selection of mirrors on a trial-and-error basis. Short referred to this method
as ‘marrying the specula’.21
3. Introduction in the northern Netherlands
3.1. Fahrenheit
The development of the reflecting telescope to a commercially producible
instrument may have been an exclusively British event, yet that does not mean that
no other attempts were made to construct a reflecting telescope.
For example, around 1712, the Gdansk-born instrument-maker, Daniel Gabriel
Fahrenheit, tried to make such a telescope. After some moving around, Fahrenheit
settled in Amsterdam in 1717. There, he devoted himself to two matters: he
produced scientific instruments, including his famous weather glasses, and also he
stimulated the sale of his instruments by being the first in the Netherlands to give
public lessons in experimental physics.22 In these lectures, Fahrenheit also reported
‘his own experiences’. Thanks to the notes of one of the listeners in his audience, we
know that Fahrenheit described how he came into contact with Newton’s Opticks
and how fascinated he was by the reflecting telescope described in that book. This
occurred in 1708, and from that moment on, Fahrenheit sought an opportunity to
‘make such an instrument operational’. He succeeded in about 1712. As Newton, in
his Opticks, had complained about both the glass and the metal of the reflecting
mirror, Fahrenheit decided to make his mirror from ‘very hardened steel’.23 The
focal length of his telescope was ‘six inches in Rhineland measurements’ (the
diameter of the mirror is not given). In addition to this, Fahrenheit introduced
some distinct changes to the telescope, as, instead of making a telescope according
to the Newtonian model, he effectively built a variation of a Cassegrain telescope.
As he stated:
afterwards it occurred to me that it was somewhat cumbersome to use the
mirror from the side and I therefore placed a round hole in the middle of
the mirror. Then, I placed a small convex mirror at such a distance from the
object mirror, that the rays of the objects (which were reflected by the large
mirror) reflected for a second time to the opening of the mirror that was made
in the large object mirror, in which opening the rays were gathered into an
image. If an ocular lens was placed behind this opening the image was
inverted and I corrected this by means of two other eyeglasses which again
21
G. L’E. Turner, ‘James Short, F.R.S. and his Contributions to the Construction of Reflecting
Telescopes’, Notes and Records of the Royal Society of London, 24 (1969), 91–108. Reprinted in G. L’E.
Turner, Scientific Instruments and Experimental Philosophy 1550–1850 (London, 1990), 91–108, esp. 95,
99.
22
Concerning Fahrenheit’s activities in the Netherlands, see E. Cohen and W. A. T. Cohen-De
Meester, ‘Daniël Gabriel Fahrenheit’, Chemisch Weekblad, 33 (1936), 1–58 and 34 (1937), 1–11 (pages
reprint). Partly published in the German language in Verhandelingen der Kon. Akad. van Wetenschappen,
Afd. Natuurkunde (Eerste sectie), 16, No. 2 (1936).
23
At that time, the term ‘steel’ was also used for alloys of copper and tin. See Chr. Wolff, Grondbeginzelen van alle de Mathematische Weetenschappen (Dutch translation by J. C. von Sprögel,), Part 3
(Amsterdam, 1739), 49.
The Reflecting Telescope in the Netherlands
413
brought the image the right way up, in the same manner as was demonstrated
in telescopes with three lenses.24
Yet, Fahrenheit was not satisfied with his result. The mirrors remained a problem.
Although the ‘steel’ he used could be better polished than any other metal, the
material was less effective in reflecting the light. The desired effect was therefore ‘by
a long way not so great, as it otherwise could have been’. It seems that Fahrenheit
made no further attempts to construct a reflecting telescope. His Amsterdam
audience only heard his theoretical explanations. From Fahrenheit’s correspondence, it is apparent that he made at least two reflecting telescopes. In 1716, shortly
before his arrival in Amsterdam, he had given both away. The first instrument was
sent to the German philosopher, Leibnitz, and a second example went to the elector
of Saxony at Dresden. Fahrenheit had tested both instruments by observing the
satellites of Jupiter. It is a pity that nothing is known about the fate of these two
telescopes.25 It seems, however, that Fahrenheit’s efforts had no influence on the
development of the reflecting telescope elsewhere in Europe. Equally, he played no
observable role in the process of the introduction of the reflecting telescope into the
Low Countries.
3.2. English import
In 1724, when the Utrecht professor, Petrus van Musschenbroek, was allowed
to set up the local Turris astronomica with new instruments, a reflecting telescope
was still out of the question.26 In view of the English developments—the tests of
Hadley’s prototype were only just published—this was scarcely possible. Such a
telescope simply was not available on the market.
It was probably the English Newtonian, J. Th. Desaguliers, who introduced the
instrument to Van Musschenbroek. In the early 1730s, Desaguliers crossed the
North Sea a few times for a successful tour, visiting a number of Dutch cities. In
England, Desaguliers had acquired great fame, not only through an impressive
scientific career, but also as a popularizer of Newtonian physics. He was a skilled
experimenter and an accomplished technician, but above all else, he was renowned
as a public lecturer. Desaguliers amazed his public with spectacular demonstrations
in which entertainment and commerce seemed to be as important as the scientific
component. In any case, the show element that Desaguliers incorporated in his
lectures (mostly given in the French language) was there to stay. With him, the
physique amusante made its debut in the Netherlands.
The tour of Desaguliers in the Netherlands was well organized and was
24
J. Ploos van Amstel Czn., Natuurkundige lessen van Daniel Gabriel Fahrenheit over de GezichtDoorzicht en Spiegelkunde, alsmede over de Waterweeg- en Scheijkunde, in onderscheidene bijeenkomsten
door hem afgehandeld. Manuscript, 1718–1719 (Univ. Libr. Leiden, PBL 772). The description of
Fahrenheit’s telescope is on p. 95.
25
Fahrenheit to Leibnitz, 1 June 1716, in P. van der Star, Fahrenheit’s Letters to Leibnitz and
Boerhaave, Amsterdam, 1983, 69. There is no mention of Fahrenheit’s optical instruments in H.
Schramm, Astronomische Instrumente: Katalog Dresden: Staatlicher Mathematisch-Physikalischer Salon
(Zwinger, 1987).
26
G. W. Kernkamp, Acta et Decreta Senatus. Vroedschapsresolutiën en andere bescheiden betreffende
de Utrechtse Academie, 2 (Utrecht, 1938), 290; See also Lucie Miedema, Resolutiën van de vroedschap van
Utrecht, betreffende de academie (Utrecht, 1900), 207–8; 211–13; 219 and J. C. Deiman, ‘Het
instrumentarium van de Utrechtse Sterrenwacht’, Tijdschrift voor de Geschiedenis der Geneeskunde,
Natuurwetenschappen, Wiskunde en Techniek, 10 (1987), 174–89.
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surrounded by considerable publicity. The promotion—perhaps even the sale—of
scientific instruments was clearly a subsidiary aim. In his performances, Desaguliers
demonstrated several new instruments, including the reflecting telescope. According
to the notes made by one of his (Rotterdam?) audience, whose illustrated booklet
was published in Amsterdam at the end of 1731, Desaguliers had praised the
considerable qualities of the instrument.27
In 1732, Desaguliers arranged a meeting with Van Musschenbroek in Utrecht,
where the latter ordered Desaguliers’ orrery for the cabinet of the university. On
that occasion, Van Musschenbroek probably ordered a reflector for his own
cabinet, for shortly thereafter, Van Musschenbroek and Desaguliers exchanged
letters, discussing inter alia the properties of a reflector, made by the London-based
instrument-maker, Edward Scarlett.28 This was probably the Newtonian telescope
with an octagonal wooden tube, now present in the collection of the Leiden
Museum Boerhaave. Somewhere between 1736 and 1739, Scarlett also supplied Van
Musschenbroek with a 2-foot-long Gregorian telescope, with a cylindrical brass
tube. In 1739, Van Musschenbroek described both pieces in the second edition of
his Dutch textbook on physics.29
Another early example of a reflecting telescope in the Netherlands was the
instrument imported in 1734 by the Leiden professor ‘s-Gravesande for the
university observatory. This was a 7-foot Newtonian telescope with an octagonal
wooden tube, bought directly from George Hearne in London. The instrumentmaker received 862 guilders, a payment equivalent to ‘s-Gravesande’s annual salary
as a university professor.30 At about the same time, the Amsterdam merchant
Johannes (John) de Lange (FRS, 1735) must have acquired a set of reflecting
telescopes. When, in February 1737, a spectacular comet appeared in the
Amsterdam sky, De Lange was able to make observations with a 7-foot Newtonian
from Hearne and a Gregorian from an unknown-maker.31 In that same year, the
Amsterdam mathematician, Nicolaas Struyck, also made use of a 7-foot reflecting
telescope made by Hearne. On this occasion, the moon and the planets could be
observed. In view of the costly nature of Hearne’s reflecting telescope, this may
27
[J. Th. Desaguliers], Korte Inhoud der Philosophische Lessen (Amsterdam, 17322), 185–6; Plate XII,
fig. V. For Desaguliers’ tour in Holland, see M. J. van Lieburg, ‘De Geneeskunde en
natuurwetenschappen binnen de Rotterdamse geleerde genootschappen uit de 18e eeuw’, Tijdschrift
voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, 1 (1978), 14–22; 124–
43 and H. J. Zuidervaart, Van ‘Konstgenoten’ en Hemelse Fenomenen. Nederlandse Sterrenkunde in de
Achttiende Eeuw (Rotterdam, Erasmus Publications, 1999), 71–82.
28
J. Th. Desaguliers to P. van Musschenbroek, November 27, 1733. (Archive Van Musschenbroek,
Museum Boerhaave, Leiden, inventory no. 138-b).
29
Both unsigned telescopes are now in the collection of Museum Boerhaave, Leiden. That Scarlett was
the constructor of the Newtonian telescope is stated by Van Musschenbroek in the 1739 edition of his
textbook (note 18), 628–35 and plates XXI and XXII. The Gregorian telescope is attributed to Scarlett in
the catalogue of the auction sale of Van Musschenbroek’s cabinet in 1762. The Leiden University
purchased both telescopes at this auction. See Collectio exquisitissima instrumentorum, [. .], vir
celeberrimus Petrus van Musschenbroek (Lugdunum Batavorum, Luchtmans, 1762), nos. 401 and 405 (a
copy of this catalogue is in the library of Museum Boerhaave, Leiden). See also E. Engberts, Descriptive
Catalogue of Telescopes in the National Museum of the History of Science (Leyden, 1970), 15–17, 23–4
and figs. 4 and 7.
30
The Hearne telescope, acquired by ‘s-Gravesande in 1734, is now in the collection of Museum
Boerhaave, Leiden. The original mirrors were replaced in 1750 by components made by the Frisian
telescope-builder, Jan van der Bildt. See Engberts (note 29), 13–14 and fig. 3.
31
P. van Aken to P. van Musschenbroek, 4 March 1737 (Archive Van Musschenbroek, Museum
Boerhaave, Leiden, inv. no. 251-c).
The Reflecting Telescope in the Netherlands
415
have been the same instrument.32 Immense wealth also enabled Pieter Gabry, a
retired lawyer in The Hague, to become the proud owner of a 4-foot Newtonian
from Hearne.33 Without exception, all early reflecting telescopes encountered in the
Netherlands were produced in England. Also, all Dutch users or owners mentioned
here were (or became) Fellows of the Royal Society of London, which underlines the
importance of this organization, not only as a centre for scientific communication
but also as a dissemination point for scientific instruments. Moreover, the article
about the development of the reflecting telescope, published by Desaguliers in 1735
after his return to England, was immediately translated into the Dutch language.
Also, this publication will have contributed to the Dutch familiarity with this
instrument.34
3.3. The Van Musschenbroek Workshop
The sales catalogues of the Leiden instrument-maker, Jan van Musschenbroek,
brother of the aforementioned Petrus van Musschenbroek, confirm that the
reflecting telescope was introduced into the Netherlands around 1735.35 Whereas,
until 1731, Jan van Musschenbroek offered only refracting telescopes, from 1736
onwards he also offered reflecting telescopes. More precisely, Van Musschenbroek
offered: ‘a most beautiful Gregorian telescope with new inventions of 16 inches on a
graceful foot’. This instrument could be obtained for 70 guilders. A somewhat
bigger model of 27 inches, also supplied with a tripod, cost twice as much. Three
years later, in 1739, the assortment was expanded with a larger Newtonian
telescope, this time 4 foot in length. It was offered for sale for the respectable price
of 255 guilders.36 Van Musschenbroek probably imported these instruments directly
from England, for, although Jan van Musschenbroek had an unmistakable interest
in the ‘respectable Gregorian telescopes’ (the letters he left behind contain various
calculations concerning the desired form of telescopic mirrors), no reflecting
telescopes made by the Van Musschenbroek workshop are known.37
32
N. Struyck, Inleiding tot de Algemeene Geographie, (Amsterdam, 1740), 21. In 1749, John de Lange
signed Struyck’s letter of introduction to the Royal Society of London. Another signature on this
document was placed by James Short, the famous constructor of reflecting telescopes. See: H. J.
Zuidervaart, ‘Early Quantification of Scientific Knowledge: Nicolaas Struyck (1686–1769) as a Collector
of Empirical Data’, in The Statistical Mind in a Pre-Statistical Era: The Netherlands 1750–1850, edited by
P. M. M. Klep and I. H. Stamhuis (Amsterdam, 2002), 125–48.
33
P. Gabry, Observationes Meteorologicae Constitutionis Atmosphaerici Aëris Nostri (The Hague,
various years, 1745–1768).
34
J. Th. Desaguliers, ‘Berigt wegens de uitvinding, verbetering en volmaaking van de terugkaatsende
verrekykers’, Uitgeleeze Natuurkundige Verhandelingen, 2 (1736), 129–77. The latter article was a
translation of the ‘Appendix’ mentioned in note 18.
35
The first known ‘second-hand’ reflecting telescope was auctioned at Amsterdam in 1740 (auction
sale catalogue of the library of Johannes van Rooye, ‘medical candidate’. Univ. Lib. Amsterdam,
Collection VBBB, no. 144).
36
The Van Musschenbroek sale catalogues are reproduced in P. de Clercq, At the Sign of the Oriental
Lamp. The Musschenbroek Workshop in Leyden, 1660–1750 (Rotterdam, 1997). In 1744, Jan van
Musschenbroek delivered a Newtonian telescope to the Amsterdam merchant J. J. de Bruyn for 250
guilders (Van Musschenbroek archive, Museum Boerhaave, Leiden, inventory no. 251-c).
37
The preserved manuscripts of Jan van Musschenbroek contain several documents concerning the
optics of a Gregorian telescope (University Library Leiden, PBL 240–67). See also J. van Musschenbroek
to P. van Musschenbroek, 3 October 1736 (Archive Van Musschenbroek, Museum Boerhaave, Leiden,
inv. no. 251-c). Today, only one (refracting) telescope from the Van Musschenbroek workshop is known
Huib J. Zuidervaart
416
4. Amsterdam ‘virtuosi’ and their interest in optics
If even the Van Musschenbroek workshop gave up the notion of constructing
reflecting telescopes—and they were, after all, the most experienced Dutch instrumentmakers with considerable experience in the crafting of metals—what could have
possessed a dilettante, such as the Amsterdam merchant Van de Wall, to think he
could be successful in this pursuit? After all, to be successful in such an undertaking, one had to satisfy a number of criteria:
there had to be sufficient motivation: both to start and to persist;
the necessary materials had to be at one’s disposal;
the required knowledge needed to be obtained, both theoretical and practical;
those who possessed this expertise, had to be prepared to exchange it with
others;
. the results obtained had to be testable.
.
.
.
.
4.1. Merchant-scientists
An answer to the question as to how Van de Wall could be successful in his
undertaking requires a better understanding of the scientific climate in Amsterdam
and the phenomenon of the merchant-scientist present there. Van de Wall’s interest
in optics was, namely, not a matter of chance. The interest of the Amsterdam ‘circle
of virtuoso’ for scientific novelties, including optics and associated instruments, is
documented in various sources.
In part, this interest originated in the early seventeenth century. At that time,
the Republic of the Seven United Dutch Provinces was the only republic of
significance in Europe. So, Royal patronage of the arts and sciences was unknown
here. However, what the Netherlands lacked in royal and aristocratic patronage
was more or less compensated by a strong merchant culture. In the no-nonsense
climate of the merchant who traded in products from the four corners of the earth,
there was an awareness of the commercial value of knowledge. It is hardly
surprising that in Dutch society, there was a tradition of the merchant-scholar, with
an eye open, not only for the world of trade, but also for the world of science.
Already in 1632, Caspar Barlaeus introduced the phrase Mercator Sapiens in a
famous speech to the Amsterdam Athenaeum (a kind of lower university). He then
referred to the fact ‘that there exists a sound relationship between commerce and
the study of literature and philosophy’.38 Money was important, as it enabled the
(Boerhaave Museum, Leiden). Whether this instrument was made by Jan van Musschenbroek himself or
was only retail remains unclear. However the auction sale catalogue of Jan van Musschenbroek’s library
and workshop mentions amongst the tools only a polishing dish (no. 226) and some ‘flat pieces of glass
for grinding into telescope lenses’ (no. 233). Mirrors for reflecting telescopes are not mentioned. Only
three little Gregorian telescopes were in stock (nos. 136–138, of 1 foot, 6 inches and 4 inches). So, retail
seems to be the most probable situation for the Van Musschenbroek workshop. See P. de Clercq, ‘A
remarkable family piece. A hand-held telescope from the Musschenbroek workshop’, Bulletin of the
Scientific Instrument Society, Sept. 2000 and Catalogus librorum [. .] quibus uses est JOANNES VAN
MUSSCHENBROEK, [. .] Cui adjecta sunt instrumenta, [. .] et machinae diversae aliae ab ipso
fabrefactae (Lugdunum Batavorum, Luchtmans), 1749. Photocopy in Museum Boerhaave, Leiden, taken
from the original catalogue in the library of the Hungarian Academy of Sciences, Budapest.
38
C. Barlaeus, Mercator Sapiens. Oratie gehouden bij de inwijding van de Illustere school te Amsterdam
op 9 januari 1632; met Nederlandse vert. en inl. uitg. door S. van der Woude (Amsterdam, 1967). See also
H. J. Cook, ‘The Moral Economy of Natural History and Medicine in the Dutch Golden Age’, in W. Z.
Shetter and I. van der Cruysse, Contemporary Exploration in the Culture of the Low Countries
(Bloomington, 1996), 39–47.
The Reflecting Telescope in the Netherlands
417
merchants to pay for the bearers of scientific knowledge, such as books, natural
curiosities and scientific instruments. So, already in the seventeenth century, there
were many in Amsterdam who were interested in telescopes, burning mirrors,
or other optical phenomena. For example, the mayor of Amsterdam, Johannes
Hudde, was known as an outstanding mathematician but also enjoyed fame as
a connoisseur of the practical optics. Around 1670, Hudde corresponded with
Spinoza and Huygens about the design of optical instruments. The polishing
dishes designed by Hudde for lenses were highly valued by connoisseurs.39 And
there were more of these enthusiasts. The Amsterdam merchant, Ameldonck Block,
not only traded in large burning mirrors made by von Tschirnhaus, but also took
care of the Dutch translation of Proeve der Deurzichtkunde [Treatise on Dioptrics]
by Nicolaas Hartsoeker in 1699. In this book about various optical phenomena,
there is also an extensive passage about the polishing of telescope lenses.40 In 1697,
one could go to the Kalverstraat in Amsterdam for ‘highly crafted telescopes
containing four lenses’ and ‘other sorts of telescopes, microscopes, spectacles’ and
‘other curiously cut lenses belonging to optics and perspectives’.41 A few years
later, the ‘philosopher mathematician’, Pieter Blom, lectured in natural philosophy
and mathematics at a Collegium Mathematicum. According to his advertisement
in the Amsterdamse Courant, optics also belonged to the ‘physical sciences’ taught
by him.42
Optical instruments were also abundantly present in the specialized cabinets of
scientific instruments that were formed at the beginning of the eighteenth century.
A man such as Fahrenheit clearly used this trend to his advantage. His lessons,
which commenced in 1717, not only satisfied local demand for information but also
generated demand for the instruments used by him. As an instrument-maker, he
would happily have met these wishes of the ‘market’. In principle, this demand was
for the entire range of scientific instruments, but Fahrenheit’s invention of both the
projection microscope and the heliostat clearly indicated a fertile ground for the
practical optics in the high society of Amsterdam. Around 1740, bankers such as
George Clifford and Hendrik de Raad managed to make a good impression with
Fahrenheit’s solar microscope.43 Clifford’s instrument cabinet, auctioned in 1760,
also contained other optics, including an example of Fahrenheit’s heliostat and a
39
W. N. A. Klever and J. Van Zuylen, ‘Insignis Opticus. Spinoza in de geschiedenis van de optica’,
De Zeventiende Eeuw, 6 (1990), 47–63. See also: R. Vermij, ‘De Nederlandse vriendenkring van E.W. von
Tschirnhaus’, Tijdschrift voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en
Techniek, 11 (1988), 153–78.
40
N. Hartsoeker, Proeve der Deurzichtkunde (Amsteldam, Jan ten Hoorn), 1699, 91. See also M. R.
Wielema, ‘Nicolaas Hartsoeker (1656–1725). Van mechanisme naar vitalisme’, Gewina 15 (1992), 243–61.
41
Amsterdamsche Courant, 7 July 1697. cf. Leidsch Jaarboekje, 1953, 113. These optical instruments
were made by François Veeckens of Leiderdorp.
42
P. C. J. van der Krogt, Advertenties voor kaarten, atlassen, globes, e.d. in Amsterdamse kranten,
1621–1811 (Utrecht, 1985), no. 263.
43
The invention of the solar microscope is often attributed to Johann Lieberkühn, who demonstrated
the instrument in 1740 in London. His ‘claim’ is denied by the Dutch translators of two English books on
optical instruments. They both identify Fahrenheit as the inventor. Fahrenheit made this ‘solar or dark
room microscope’ for two Amsterdam bankers. One of these was George Clifford, the well-known
maecenas of Linnaeus. It was said that Lieberkühn saw the instrument during a visit to Clifford’s
cabinet. Around 1716, Fahrenheit also invented another optical instrument, the ‘heliostat’, also present in
Clifford’s cabinet. See H. Baker, Het Microscoop Gemakkelyk Gemaakt (Amsterdam, 1744), 20; R.
Smith, Volkomen Samenstel der Optica (Amsterdam, 1753), 642 and A. A. Mills, ‘Portable Heliostats
(Solar Illuminators)’, Annals of Science, 43 (1986), 369–406, esp. 375–6.
418
Huib J. Zuidervaart
strikingly large Newtonian telescope 8 foot in length.44 The cabinet of the
Mercator-sapiens Anthony Bierens, who died in 1747, had a similar emphasis on
optical instruments. In his instrument collection, there were various telescopes,
including a Cassegrain telescope manufactured by James Short, a Gregorian
telescope with a ‘black shark’s skin tube with copper foot’, and various other
telescopes with lenses, manufactured by, among others, the Amsterdam optician,
Balthasar Sommers.45 In total, this section contained 30 objects, not counting the
microscopes.46
The travel journal of the Swedish astronomer, Bengt Ferrner, sketches a fine
picture of the scientific climate of the Amsterdam merchant-scientists. In his tours
of Amsterdam in 1759, Ferrner encountered various scientific enthusiasts, including
a number with an explicit interest for astronomy and optics. He visited the
‘Monday evening class’ of Klaas de Vries, teacher at the Mennonite seminary,
where he attended a lesson in elementary optics. He also visited a number of private
observatories such as that of the merchant, Pieter de Clercq, and the banker,
Diederik de Smeth. Ferrner was clearly impressed by the knowledge they displayed.
In De Clercq’s collection of scientific instruments, optics played a prominent role.
For example, De Clercq showed Ferrner two mirrors for a large, not-yet-assembled
8-foot telescope. The producer of these mirrors was not specified.47
4.2. The philosophical component of optics
Why was there such an emphasis on optics? The answer to this question can in
part be traced back to the seventeenth century, when there was a clear link between
the study of the sciences and the practice of general philosophy. For example, the
oldest biographer of the Dutch philosopher, Baruch de Spinoza, laid a clear
link between Spinoza’s philosophical programme and his interest for optics.48
The Spinoza expert Klever made the following comment about this programme:
‘Spinoza’s scientific philosophy is a major attempt to liberate man from his optical
illusions, or rather: to make him realise that there are optical illusions which he can
never get rid of as they are caused by natural mechanisms’.49 An important aspect
of this philosophical ‘quest for truth’ was the human perception. Spinoza was fully
aware that this perception was partly generated by the eye and partly by the human
mind.50 Knowledge of optics was therefore vital for fathoming the eye’s function.
The grinding and polishing of lenses contributed to the perfection of optical
theory and were therefore useful in the ‘quest for truth’. Furthermore, with these
lenses, optical instruments, such as telescopes and microscopes, could be
constructed, which in turn could extend true knowledge. In this manner, empirical
44
Van der Krogt (note 42), no. 1165. A similar ‘unusual Newtonian telescope of around 7 feet’ was
auctioned at Amsterdam in 1762 (no. 1184).
45
Balthasar Sommers made spectacles and other optical instruments. In 1744, his widow sold pocket
microscopes in her shop on the Reguliersgracht in Amsterdam. See Baker (note 43), 8.
46
J. A. Bierens de Haan, ‘Het huis van een 18e eeuwse ‘‘Mercator Sapiëns’’’, Jaarboek van het
genootschap Amstelodamum, 49 (1957), 110–28.
47
G. W. Kernkamp, ‘Bengt Ferrner’s dagboek van zijne reis door Nederland in 1759’, Bijdragen en
mededelingen van het Historisch Genootschap, 31 (1910), 314–509, esp. 365. Also published by S. G.
Lindberg, [ed.], Resa i Europa 1758–1762, Uppsala, 1956.
48
J. M. Lucas, La vie et l’esprit de Mr Benoit de Spinosa (1719), cited in Klever and Van Zuylen (note
39), 47.
49
Klever and Van Zuylen (note 39), 57.
50
Baruch de Spinoza to Jarig Jelles (an Amsterdam merchant), 3 March 1667, cited in Klever and
Van Zuylen (note 39), 55–7.
The Reflecting Telescope in the Netherlands
Figure 1.
419
A merchant-scientist and astronomer, probably Jan De Munck, and his family
gathered around a small reflecting telescope, c.1750 (Rijksmuseum, Amsterdam).
experimentation, alongside mathematical reasoning, turned out to be an effective
and permissible means of practising science.
Can this seventeenth-century motivation also be applied to the eighteenthcentury situation? At first, this would seem to be problematic. The rational way of
reasoning of the seventeenth-century Spinozists differed strongly from the early
eighteenth-century dilettantes. In fact, the early Dutch Newtonians firmly opposed
the philosophy of Descartes and Spinoza, regarded as atheistic.
As the followers of Descartes and Spinoza in particular had applied themselves
to physics and mathematics, for a time the interest in science in the Netherlands
had diminished, as a consequence of their being discredited. This attitude changed
with the introduction of Newtonianism. One of the factors of this breakthrough
was the publication, in 1715, of the physico-theological book, Het Regt gebruik der
Wereltbeschouwingen [The correct use of Philosophy] by the physician, Bernard
Nieuwentijt.51 This book was characterized by two issues. On the one hand,
Nieuwentijt attacked the ‘atheistic’ philosophy of Descartes and Spinoza; on the
other hand, Nieuwentijt designated Newton’s manner of thinking as being the sole
51
J. Bots, Tussen Descartes en Darwin. Geloof en natuurwetenschap in de achttiende eeuw in Nederland
(Assen, 1972); R. Vermij, Secularisering en natuurwetenschap in de zeventiende eeuw: Bernard Nieuwentijt
(Amsterdam, 1991).
420
Huib J. Zuidervaart
correct way. Nieuwentijt pleaded for the Newtonian cause, as this attitude allowed
plenty of room for divine provision. In doing so, he presented natural science as a
key to glorifying God. With this approach, scientific interest received a new legitimacy. As a result, in the following decades, Dutch interest in science enjoyed a
strong revival. In 1736, the Utrecht professor, Van Musschenbroek, even wrote in
his textbook on physics: ‘Never in the United Netherlands has one met more
gentleman-physicists than now at present in this time: for not only is this science
blossoming under most scholars, but also amongst many leading merchants and
people from all walks of life’.52
Nevertheless, in practice, the expression of the scientific interest seems to have
changed very little. Optics still was important as a philosophical tool in understanding human perception. A good example of this enduring role is the
Amsterdam merchant, Lambert ten Kate (1674–1731). This all-round man has
been described as ‘a curious aesthetist, who besides being an expert on art and a
collector, is a grain merchant by trade and a linguist, theologian, physicist and
mathematician by vocation’.53 Ten Kate was an early follower of Newton and also
one of the first admirers of Fahrenheit. As early as 1717, he wrote an article about
Fahrenheit’s instruments. In this, he devoted particular attention to the optical
phenomena produced in two of his barometers, which was later shown to be of
electrostatic nature.54 Ten Kate’s cabinet of scientific instruments, auctioned after
his death in 1732, reflects his particular interest in optics. The catalogue lists
numerous optical instruments, including ‘an ivory microscope’ with a lens arrangement following Ten Kate’s own instructions.55 Inspired by Newton’s Opticks, Ten
Kate carried out some optical experiments with his nephew, Jan Willink, in 1716.56
These experiments were published posthumously by Johannes Nettis. This Mennonite
medic would become one of the first specialist ophthalmologists in the Netherlands.57
A study by Nettis on perspective has also been preserved. Ten Kate was
also interested in this subject. The German scholar, von Uffenbach, who visited
Ten Kate in 1711, remembered how during that visit a heated discussion arose
concerning the portable camera obscura developed by ‘s-Gravesande. In commenting on this instrument Ten Kate adopted the position that it was useless.
Owing to lens imperfections, the image was distorted, and consequently, the
perspective of image was not faithful to the original.58 So, in Ten Kate’s optical
52
P. van Musschenbroek, Beginselen der Natuurkunde (Leiden, 1736), preface.
J. G. van Gelder, cited in C. L. van Cate, Lambert ten Kate Hermanszoon (1674–1731), taalgeleerde
en kunstminnaar (Utrecht, 1987), 178.
54
L. ten Kate, ‘Lettre écrit à l’Auteur’, Bibliothèque Ancienne et Moderne, 7-II (1717), 223–31. See
Van Cate (note 53), 36–41.
55
Catalogus [ …] nagelaten door Lambert te Kate, Hermansz (Amsterdam, I. Tirion, 1732), 86–9
(Rijksmuseum, Amsterdam).
56
L. ten Kate, ‘Proef-ondervinding over de scheiding der coleuren, [ …] in navolging eener proefondervindinge in Newton’s gezichtkunde’, Verhandelingen uitgegeven door de Hollandsche Maatschappij
der Wetenschappen, 3 (1757), 17–30.
57
Johannes Nettis (1707–1777) studied at the Mennonite Seminary in Amsterdam until 1729. In later
years, he worked as a physician and Mennonite counsellor in Middelburg. In this city, he also led a
Physisch College, a study group on science. In 1745, he was appointed ‘town oculist’, and in 1751, he
became the ‘oculist’ of Stadholder Willem IV. See Nieuw Nederlandsch Biografisch Woordenboek, II, 983.
An unpublished study on perspective by Nettis is preserved in the Archives of the Hollandsche
Maatschappij der Wetenschappen (Haarlem).
58
Zacharias Conrad von Uffenbach, Merkwürdige Reisen durch Niedersachsen, Holland und Engelland
[in 1711], vol. 3 (Ulm, 1754), 651–6.
53
The Reflecting Telescope in the Netherlands
421
studies, the philosophical ‘quest for truth’ also played a role. Being an art collector,
Ten Kate’s optical interest was also fed by his aesthetic experience of art and decorative
objects. In each artistic experience, ‘light’ takes care of the transfer of information. The
role of the human eye in the reception of this information was crucial. That Fahrenheit
made models of the eye to explain its optics was therefore a natural thing to do. Others,
such as the Amsterdam merchant, Hendrik Feyt (1699–1790), made similar models.
This physico-theologically inspired man had gained a considerable reputation as an
expert on optics. A model eye constructed by Feyt served in 1746 as a reference in the first
published Dutch study on the optics of the eye.59
An aesthetic perspective was possibly also one of the reasons for the optical
interest shown by Cornelis Ploos van Amstel (1726–1798). This timber merchant,
property agent, art collector, publisher of prints, and artist was undeniably
influenced by Ten Kate, whose notes including those on art criticism, were copied
by Ploos for his own use. Also, the father of Ploos had known Ten Kate. Like Ten
Kate, Ploos senior had attended Fahrenheit’s lectures, and his notebooks were
lovingly looked after by his son, Cornelis. The knowledge on optics presented in
these lecture notes would continue to interest him as a creative artist for the rest of
his life. This interest was also expressed in an instrument cabinet containing mostly
optical instruments.60 Following in his father’s footsteps, Ploos also chose to follow
physics lessons, this time under Benjamin Bosma, a lecturer who, after obtaining his
doctorate at Franeker, settled in Amsterdam, where, from 1753 onwards, he took
over a sizeable part of the private market for physics lessons. Here, Ploos met
various lovers of optics, including the brass founder, Carl Ulrich Bley. His role in
the construction of optical instruments will be dealt with later in this article.61
Other experts in optics were included in Ploos’ circle of acquaintances, including the
previously mentioned Hendrik Feyt62 and his pupil in optics, the philosopher and
aesthetist, Frans Hemsterhuis (1721–1790). Hemsterhuis also had a great passion
for optics, and also in his case, this interest seemed to have been prompted by a
philosophical quest for truth and the role of perception in this.63
4.3. Jacobus van de Wall and his ‘great telescope’
It is against this background of ‘merchant-scientists’ driven by philosophical
curiosity, amusement, and status that we can position the rich Amsterdam
59
Petrus Camper, Optical Dissertation on Vision, 1746. Facsimile of the Original Latin Text, With a
Complete Translation and Introduction by G. Ten Doesschate (Nieuwkoop, 1962), 2. See also Michael J.
Petry, ‘Hemsterhuis on Mathematics and Optics’, in The Light of Nature: Essays in the History of Science
presented to A.C. Crombie, edited by J. D. North and J. J. Roche (Dordrecht, 1985), 209–39. Feyt and his
eye model are discussed on pp. 212–3. An ‘artificial eye’ made by Fahrenheit is currently in the University
Museum of Groningen. A similar model of the human eye, made by A. de Penedo, was present in the
large cabinet of scientific instruments collected by the Amsterdam merchant and art collector Aron de
Joseph de Pinto. See his auction catalogue (Amsterdam, April 1785), no. 10.
60
A.F. Gogelein, ‘Wetenschappelijke instrumenten, optische werktuigen en rariteiten’, in: Th.
Laurentius, J.W. Niemeijer and G. Ploos van Amstel, Cornelis Ploos van Amstel 1726–1798.
Kunstverzamelaar en prentuitgever, Assen, 1980, 87–90. On the friendship of Ploos van Amstel with
Ten Kate, see Van Cate (note 53), 60; 74.
61
Marja Keyser, ‘Het intekenboek van Benjamin Bosma: natuurwetenschappelijk en wijsgerig
onderwijs te Amsterdam, 1752–1790; een verkenning’, Jaarverslagen Kon. Oudheidkundig Genootschap,
124–7 (1986), 65–81.
62
Laurentius [et al.] (note 60), 380. Feyt received a presentation copy of the first experimental efforts
by Ploos with colour printing.
63
Peter Sonderen, Het sculpturale denken. De esthetica van Frans Hemsterhuis (Leende, 2000), 30–1.
Petry (note 59), 232; Michael J. Petry, J. L. Borst, and G. J. L. Scheurwater, Frans Hemsterhuis.
Waarneming en werkelijkheid (Baarn, 1988), 138.
422
Huib J. Zuidervaart
merchant, Jacobus van de Wall, whose telescope (mentioned in the Introduction)
was left to the University of Leiden in 1782. Together with his brother, Van de Wall
owned a medium-sized mercantile house, the ‘Company Jacobus & Johannes van de
Wall’, situated on the Kalverstraat in Amsterdam, which at that time was the
principal trade centre in Amsterdam. The business activities of the company were
quite diverse. If we take a look at the many loading contracts kept in the
Amsterdam notarial archive, then apart from banking activities, most efforts
concerned the dispatching of ships throughout the world. Grain, seeds, peas, flax,
rye, oats, hemp, codilla, camphor, and wine, but also millstones and herring, were
shipped to a wide range of places in Russia, Scandinavia, England, Scotland, the
Netherlands, France, Spain, and Portugal. Trade was also conducted with places in
the East and West Indies, although in these cases, trade mainly concerned goods
such as wood, minerals, metals, and diamonds.64 Their main trading activities were
centred on Portugal. When the Portuguese capital, Lisbon, was destroyed by a
powerful earthquake in 1755, one of the eye-witness accounts published in the
Netherlands came from employees of Van de Wall’s company. This is also the first
occasion on which we learn something about Jacobus van de Wall’s scientific
interests. In this publication, he was referred to as a ‘merchant in Amsterdam and
admirer of fine arts and sciences’.65
It seems that he was a follower of one of the scientific practitioners active in
Amsterdam in about 1740. A direct link can be made with one of them, namely
Johan Christoffel von Sprögel, a physician born in Hamburg and trained in Halle.
Von Sprögel had settled in Amsterdam in about 1720, where he soon showed
himself to be an erudite man with considerable practical and theoretical skills.
In 1722, he obtained a patent for a ‘newly invented fire-extinguishing machine’.66
He also translated most of the textbooks by the German natural philosopher,
Christiaan Wolff, into Dutch.67 According to a preserved prospectus, von Sprögel
resolved in 1736 to provide special lessons in physics and chemistry for a
‘collegium’ of apothecaries and other enthusiasts.68 Van de Wall may have attended
these lectures. In any case, von Sprögel entered into a contract with Van de Wall’s
company in 1741, in connection with an intended mining project by the brothers in
Brazil. As ‘master smelter and separator of the minerals and metals’, von Sprögel
would have to supervise the construction of ovens, furnaces, and ‘everything
associated with the work in the mines’. If required, he also needed to travel to
Lisbon and then on to Brazil with ‘students and fellow masters’. It is not clear to
64
Municipal Archives Amsterdam, protocols of the Notaries H. de Wolff (1741), B. Phaff (1744–
1759), D. v.d. Brink (1764–1773; 1784); Th. D. de Marolles (1754–1770), N. Wilthuyzen (1771); C. van
Homrigh (1773–1774); W. Decker (1778); S. Dorper (1771–1783) and E. M. Dorper (1782–1785).
65
‘Memorie’, printed in J. F. Drijfhout, ‘Nadere aanmerkingen over de oorzaak en werkingen der
waterberoeringe van den Isten november 1755’, Verhandelingen uitgegeven door de Hollandsche
Maatschappij der Wetenschappen, 7-I (1763), 182.
66
G. Doorman, Octrooien voor uitvindingen in de Nederlanden uit de 16e–18e eeuw (‘s-Gravenhage,
1940), 308. Von Sprögel originally applied for a patent together with Zacharias Gryl, who died in 1722.
67
For von Sprögels translations, see M. R. Wielema, ‘Christiaan Wolff in het Nederlands. De
achttiende-eeuwse vertalingen van zijn Duitstalig oeuvre (1738–1768)’, Geschiedenis van de wijsbegeerte in
Nederland, 1 (1990), 55–72. Reprinted in his thesis, Ketters en Verlichters. De invloed van het spinozisme
en wolffianisme op de Verlichting in gereformeerd Nederland (Free University of Amsterdam), 1999, 116–9.
68
Programma ad Collegium Chymico-pharmaceuticum Dogmaticum [ …] in het welke Doctor Joann
Christoffel van Sprögel, [. .] poorter en medicijn-meester tot Amsterdam, zijnen dienst presenteert aan alle
liefhebbers (Amsterdam, 1736) (Library of the University of Amsterdam).
The Reflecting Telescope in the Netherlands
423
what extent this actually happened, but as von Sprögel can no longer be traced in
the Amsterdam archives after 1743, it is reasonable to assume that he did indeed
depart to Brazil.69
In view of von Sprögel’s varied expertise—he possessed medical, technical,
physical, chemical, and metallurgical knowledge—it is plausible that he played a
role in the development of Van de Wall’s interest in optics. Von Sprögel had
also translated Wolff’s optics, catoptrics, dioptrics, perspectives, and spherical
trigonometry into Dutch, and in the ‘preface’ of this work, it was stated that
the book was in part intended for practical usage. Or, as von Sprögel put it:
‘whoever is interested in some optical handiwork, will also be able to find
instruction in how to make such instruments for themselves’.70 This is precisely
what his employer, Jacobus van der Wall, did! As the German text of Wolff’s
book dates from 1719, the reflecting telescope is not mentioned, yet the book does
contain instructions for making reflective material. Also, the casting and polishing
of ‘round or spherical mirrors’ is covered in von Sprögel’s translation.71 Van de
Wall, who must have started to construct telescopes in about 1740, had other
printed material to refer to. In 1738, the first printed manuals for the construction
of a reflecting telescope became available. From London came Robert Smith’s
Compleat System of Opticks, and from Paris came the anonymous publication,
Construction d’un Telescope de Reflexion. It later transpired that the instrumentmaker, Claude Passement, was the author. He had set forth his own experiences in
this book, which was specifically written for those dilletants ‘who want to construct
a telescope by their own’.72 Both books were published in an Amsterdam edition. In
1741, a pirate edition of the French book was published, and in 1751, one could
subscribe to the Dutch translation of Smith’s Compleat System of Opticks.73 The
printed subscription list proves that Van de Wall ordered a copy. However, it is
highly probable that by that time, Van de Wall could have managed without this
translation, for, prior to the construction of his large telescope, Van de Wall had
already constructed some smaller reflectors, which are no longer in existence (or at
least are no longer recognized as such).74
Why did Van de Wall start constructing reflecting telescopes? To his visitors,
Van de Wall was always very clear about this matter. One such guest, the Swedish
astronomer, Bengt Ferrner, recorded in 1759 the following statement:
On the 4th [April] I was invited by Mr Van de Wal to see his astronomical
69
Municipal Archives Amsterdam, NA 8956/842, 4 August 1741.
Chr. Wolff, Grond-beginzelen van alle de Mathematische Weetenschappen, Uit het Hoogduitsch
vertaald door Joann Christoffel van Sprögel, vol. 3, (Amsterdam, 1739), ‘Voorreden’.
71
Ibidem, 49. Wolff refers here to the burning-mirrors of von Tschirnhaus. For these, see P.
Plassmeyer and S. Siebel, Ehrenfried Walther von Tschirnhaus (1651–1708). Experimente mit dem
Sonnenfeuer, Dresden, 2001.
72
The pirated version of Passemants book was printed in Amsterdam in 1741 as Construction d’un
telescope par reflexion, de Mr. Newton: ayant seize pouces de longueur, & faisant l’effet d’une lunette de
huit pieds, et de plusieurs autres telescopes [xii, 212 pp., 1 pl.]. Court and von Rohr’s statement (note 18),
220, that this edition was enlarged with additions, probably from an Amsterdam source, appears to be
wrong.
73
Jacobus van de Wall is mentioned in the list of 176 subscribers on the Dutch edition of Smith’s
book. This subscription took place in the spring of 1751. See Zuidervaart (note 27), 265–6.
74
It is probable that some of the telescopes mentioned in 1785 in the inventory of the estate of his
brother Johannes van de Wall were in fact manufactured by Johannes van de Wall (Municipal Archives
Amsterdam, NA 14692, no. 11, 17 January 1785).
70
Huib J. Zuidervaart
424
Figure 2.
Jacobus van de Wall’s telescope (Museum Boerhaave, Leiden).
observatory located some distance from the Leiden gate and see his
instruments and in particular his eight-foot telescope. He himself made the
mirrors for this and drew up the design of the telescope and everything
associated with this …. Yet in particular he pointed out to us the mirrors
The Reflecting Telescope in the Netherlands
425
for a twenty-foot reflecting telescope, which, as Mr Van de Wal informed
us, were made by him for the following reasons. Before he commenced
with the construction of mirrors he had wished to purchase a four-foot
telescope in England. Yet as he found the price to be excessive, he decided,
being experienced in the theory, to make a telescope for himself that would
be bigger than those available in England. He then commenced with the
construction of his eight-foot telescope, yet when news of this reached Mr
Short in England, he constructed two telescopes each of twelve foot in
length. However, Mr Van de Wal was not to be defeated by Mr Short
but on the contrary—if possible—wished to outdo him, and therefore he
had commenced work on these mirrors for a telescope of twenty foot. He
had not as yet had the time to try these out, although they were completely
finished.75
Various issues are mentioned in this statement: first and foremost, there is the
element of competition. From both this report and other sources, it is apparent that
Van de Wall wished to be compared with the English instrument-maker, James
Short. As a specialized telescope-maker, Short indeed charged about twice the
going rate for his instruments. The quality of Short’s products was apparently good
enough for him to command such prices. However, Van de Wall judged Short to be
extremely expensive. Driven by Dutch thriftiness, Van de Wall decided to construct
reflecting telescopes with his own hands. From the information given in the report,
this initiative can be dated back to 1742.76 At that time, Van de Wall considered
himself to be ‘experienced in the theory’. That there was sufficient knowledge
available in Amsterdam at that time has already been argued. In view of Van de
Wall’s connections with the Wolffian von Sprögel, it is likely that the latter was
involved in the project. Von Sprögel’s expertise as a ‘master-smelter’ fits in well with
the fact that Van de Wall experimented with alloys. We know more about this,
thanks to the Utrecht professor, Hennert, who in 1779 published a description of
the telescope.77 Van de Wall had told Hennert that he had achieved the best results
with Japanese or Swedish copper, combined with English tin. After ‘carrying out a
great many experiments’, the ‘learned optician’ arrived at an alloy of 32 parts
copper to 13½ parts tin. According to Van de Wall, outstanding mirrors could be
made with this reflective metal. More tin would indeed provide a shinier surface on
the mirrors, but this would result in their being more fragile and less suitable for
polishing. According to Hennert, at no time did Van de Wall doubt that larger
telescope mirrors could be constructed from his metal, as long as ‘savings are not
made on the costs or the work’. From Hennert’s account, Van de Wall outsourced
75
Kernkamp (note 47), 373–5.
Short made his first 3-foot telescope in 1741, at the request of the Earl of Macclesfield. A year later,
he produced his first 12-foot telescope (only three were made by him), this time for Charles Spencer,
Duke of Marlborough. So, the 4-foot telescope almost certainly originates from this period as well. The
oldest-known 4-foot telescope of Short (the fifth he ever made) dates from around 1752 (now in the
Observatoire de Paris). See Gerard Turner (note 21) and D. J. Bryden, James Short and His Telescopes:
an Account of the Life of James Short (1710–68), Europe’s Foremost Maker of Reflecting Telescopes:
With a Description of the Instrument Brought Together for the Bicentenary Exhibition (Edinburgh, Royal
Scotish Museum, 1968), 23–5.
77
J. F. Hennert, ‘Descriptio Telescopii Gregoriani novem pedum, a Nobil. Van de Wall,
Amstelaedamensi constructi’, in J. F. Hennert, Elementa, Optices, Perspectivae, Catoptrices, Dioptrices,
et Phaometriae (Utrecht, 1770), three unnumbered pages ‘post praefationum’. See also Hennert (note 4),
278.
76
426
Huib J. Zuidervaart
the casting work. This was carried out by the ‘artisan’ Carl Ulrich Bley, after which,
the rough mirrors were ‘with much sweat’ ground and polished by Van de Wall
himself. Bley was not a ‘run of the mill’ caster. As we shall see, during the years
1760–1765, he would play a pioneering role in the development of the Dutch
version of the achromatic telescope.
Although, over the years, many astronomers found their way to Van de Wall, it
is clear from all reports that the merchant was mainly driven by an optical, and
perhaps purely mechanical, interest.78 Van de Wall was barely interested in the
astronomical applications of his instruments. Ferrner’s travel journal gives a
good illustration of this. Although Ferrner characterized the Amsterdam merchant
as somebody with ‘a good and clear understanding’ who ‘possessed a lot of
mathematical and physical knowledge’, he missed two essential aspects in Van de
Wall’s observatory. The building lacked both an accurately laid out meridian and a
reliable pendulum clock. Therefore, Ferrner flawlessly concluded: ‘From this it is
apparent that for Mr Van de Wal it is more important to observe the heavenly
bodies and demonstrate his knowledge of optical theory with his telescopes, than it
is to make a series of direct observations, which can serve to advance the further
accuracy of astronomy’. This lack of scientific ambition was deplored. When the
French astronomer, Joseph-Nicolas de l’Isle, enquired in the spring of 1759 about
this ‘Curieux d’Amsterdam’ and his special telescope, his correspondent, Arnout
Vosmaer (the curator of the Dutch Stadholder’s scientific collections), had to
inform him: ‘The Amsterdam astronomer Mr. van de Wall … is not at all what he
seems to be. He is in no way one of the leading scientists in the field …. Still it is a
pity that such a pretty machine, of which all astronomers recognise its quality, is
not in more able hands’.79
That Van de Wall only attached value to his optical craftsmanship is confirmed
by the account of his proposed 18- or 20-foot telescope. Despite all of the effort
Van de Wall must have put into the main mirror, he literally left the finished mirror
untouched for decades, without really making an effort to construct a working
instrument. In 1759, the mirror had already been shown to Ferrner, and in 1777,
the Danish astronomer, Bugge, found this object still unused. According to Bugge,
Van de Wall had in the meantime given up on the project, as ‘parts of the telescope
and especially the support would be too heavy and too strong’.80
5. The diffusion of technical skills to Friesland?
5.1. Franeker
The optical interest of the scientific amateurs of Amsterdam appears to have
had further consequences. It is highly probable that the knowledge concerning the
construction of reflecting telescopes was transferred from Amsterdam to the
northern Dutch province of Friesland. In the second half of the eighteenth century,
this region would develop into an important centre for the construction of reflecting
78
Van de Wall’s observatory was visited by foreign astronomers such as Ferrner (1759), De
Courtanvaux, Pingré and Messier (1767) and Bugge (1777). See Kernkamp (note 47), 373–5; Journal of
François-Cesar le Tellier, Marquis de Courtanvaux, 1769 (Bibliothèque Sainte-Geneviève, Paris, mss.
no. 3010, folio 138); K. Møller Pederson and M. Dybdahl, Thomas Bugge. Journal of a voyage through
Holland and England, 1777 (preliminary edition, Aarhus, 1997), 55–65.
79
De l’Isle to Vosmaer, 22 April 1759 and Vosmaer to De l’Isle, 25 May 1759 (AN, Paris, Corr. De
l’Isle, XIV, 92 and 107).
80
Pederson and Dybdahl (note 78), 65.
The Reflecting Telescope in the Netherlands
427
telescopes. Of the 30 or so telescope-makers who worked in the Netherlands during
the eighteenth and early nineteenth century, about 20 originated from Friesland
(see table 1). And although this local development was partly a consequence of a
local tradition of extramural scientific endeavour, the origin of the Frisian preference for reflecting telescopes has never been fully clarified.81
The Frisian Academy in Franeker was the only university in the Netherlands
that, in addition to the usual university curriculum, continuously provided technical
education in the Dutch language. This special situation probably stimulated such
technical development.82 Moreover, the first Frisian builder of reflecting telescopes,
Jan Pietersz van der Bildt (1709–1791), started as a general instrument-maker at the
Frisian Academy. As the years went by, he became the most successful telescopebuilder in the Netherlands. He is therefore the best known of all of his colleagues.
Originally trained as a carpenter, Van der Bildt initially developed into a clock- and
watchmaker.83 At an Amsterdam auction, he happened to acquire some materials
and tools for the construction of flat household mirrors, and this coincidence
probably led to his running a mirror shop in Leeuwarden for a short time. In 1734,
he moved to Franeker, where he again returned to the manufacture of clocks. In
this small university town, Van der Bildt’s craftsmanship must have been noticed.
Tradition has it that the university lecturer in mathematics, Willem Andris Loré
(1679–1744), called upon Van der Bildt to maintain the university’s instrument
cabinet. Loré would also have been responsible for Van der Bildt’s retraining to
an instrument-maker. In this, Loré apparently not only instructed him but also
negotiated the sale of Van der Bildt’s products. Through Loré, Van der Bildt must
have received a reflecting telescope of English origin for repair. Clearly, as so often
happened, this mirror had lost its reflectivity over the course of time. It is
understood that Van der Bildt tried to improve the mirror by polishing it but failed.
Following this, the owner of the telescope demanded a replacement mirror to be
imported from England. This created a serious problem for the as-yet inexperienced
Van der Bildt. However, expertise from Amsterdam, mobilized by Loré, provided a
way out.
5.2. The Amsterdam connection: Tiberius Hemsterhuis and Hendrik Feyt
Loré had various contacts. As the academy lecturer of mathematics, he was on
friendly terms with Tiberius Hemsterhuis (1685–1766), until 1740 professor of
classical languages at Franeker, but in an earlier stage of his life professor of
mathematics at the Amsterdam Athenaeum Illustre. From this time in Amsterdam,
Hemsterhuis had retained some friends, and one of them was Hendrik Feyt, a key
figure amongst the scientific amateurs of Amsterdam. Feyt did come to Franeker. It
is certain that in about 1735, Feyt gave lectures in mathematics and optics at
81
H. J. Zuidervaart, Speculatie, wetenschap en vernuft. Fysica en astronomie volgens Wytze Foppes
Dongjuma (1707–1778), instrumentmaker te Leeuwarden (Leeuwarden, Fryske Akademy, 1995).
82
C. A. Davids, ‘Universiteiten, Illustere scholen en de verspreiding van technische kennis in
Nederland, eind 16e–begin 19e eeuw’, Batavia Academica, 8 (1990), 1–35, esp. 9, 11, 17, 26–27, 29 and
P. J. van Winter, Hoger beroepsonderwijs ‘avant la lettre’. Bemoeiingen met de vorming van landmeters en
ingenieurs bij de Nederlandse universiteiten van de 17e en 18e eeuw (Amsterdam, 1988).
83
J. Scheltema, ‘Levensschets van Jan van der Bildt’, in Geschied- en Letterkundig Mengelwerk, vol. 3,
st. 3 (Utrecht, 1823), 225–47; J. van der Bilt, ‘Over den Frieschen teleskopenbouwer Jan Pytters van der
Bildt (1709–1791)’, Hemel en dampkring, 39 (1941), 122–36.
428
Huib J. Zuidervaart
Franeker to the then 14-year-old son, Frans Hemsterhuis. Later in life, this young
man would gain great fame as a philosopher and an authority on optics. Even when
Feyt was already an old man, his old student, Frans Hemsterhuis, consulted him as
an expert on optical instruments. In one of his letters, Hemsterhuis described his
former teacher as ‘the oldest of all my friends, a wise man in all aspects … and the
best physicist I know of ’.84
Loré, who may have become acquainted with Feyt during one of his visits to
Franeker, must have called upon his help with respect to the issue of the telescope
damaged by Van der Bildt. According to the stories that still circulated under Van
der Bildt’s grandchildren, Feyt was very expert in the matter. In these family
stories, Feyt was described as ‘a well to do merchant, famous as a grinder of lenses
for telescopes and as an expert on dioptric instruments, who furthermore had a
reputation for possessing the best English telescopes and binoculars’. One way or
another, helped by Feyt and Loré, Van der Bildt learned to manufacture telescopic
mirrors.85 One of his first pieces was put to the test by Feyt and other ‘leading
practitioners of the physical sciences and enthusiasts’ at the observatory on top of
Feyt’s Amsterdam residence. The test demonstrated that Van der Bildt’s reflecting
telescopes compared favourably with those of English construction. Van der Bildt’s
first reflector therefore received a place of honour in Feyt’s cabinet of scientific
instruments.86
5.3. Frans Hemsterhuis and Petrus Camper
In later years, Frans Hemsterhuis kept in strong contact with Franeker. This
was not only because of his upbringing in this academic city, but also because he
was the bosom friend of Petrus Camper, who was appointed professor there in
1749.87 The two had known each other since 1740 when, in Leiden, the two families
took up residence next door to each other. Hemsterhuis shared the ‘rage de la
recherche’ with Camper. In the initial years of their friendship, this passion was
directed towards the natural sciences. Feyt, the tutor of Hemsterhuis, was also
involved in this friendship. That Camper chose an optical subject for his doctoral
thesis in 1746 can probably be ascribed to Feyt’s influence on both friends. In this
Dissertatio optica de visu, Camper refers to ‘the artificial eye constructed by the very
skilful Feith of Amsterdam’87. Also, in the diary of his Grand Tour to London in
1748, Camper mentions an experiment ‘with the loadstone of Feyth’. During the
same trip, Camper acquired a particular interest for the telescopes built by James
Short. In January 1749, Camper became acquainted with the ‘famous’ 12-foot
telescope, which Short had constructed in 1742 for the Duke of Marlborough. In
May, Camper visited Short’s workshop in London, where he saw a second example
84
Petry (note 59), 212–13. See also L. Brummel, Frans Hemsterhuis. Een Philosophenleven (Haarlem,
1925), 30; 33 and Petry (note 63), 15.
85
My interpretation differs slightly from the story presented by Scheltema (note 83), 235–6.
According to this story, Van der Bildt had contacted Feyt after the reparation of the telescope. However,
in view of the verifiable historical facts, my interpretation seems to provide a more likely scenario of the
events.
86
In 1822, this first Van der Bildt telescope was in the possession of Johannes Buys, lecturer in
Physics at the Amsterdam society ‘Felix Meritis’. See Scheltema (note 83), 239.
87
For the friendship between Camper and Hemsterhuis, see Brummel (note 84), 31 and R. P. W.
Visser, ‘Een brief van Petrus Camper aan Frans Hemsterhuis’, Documentatieblad Werkgroep Achttiende
Eeuw, 1974, 13–23.
The Reflecting Telescope in the Netherlands
Figure 3.
429
The telescope-builder, Jan van der Bildt, portrayed with one of his telescopes (City
of Franeker).
of the 12-foot telescope. (Short constructed a total of three copies of this large
instrument.) Conscientious as he was, Camper ascertained that in the construction
of such large telescopes, Short could not satisfy the ideal parabolic profile by means
of a spherical approach. Of course, ‘a hollow sphere cannot cover such a wide field,
as it gives a confused focus, because the rays in the middle are longer. This can only
be made right by the parabola’. Camper was surprised by the empirical manner in
430
Huib J. Zuidervaart
which Short solved this problem: ‘This is not done by calculation, but all has to be
adjusted through observation until it is accurate’.88 Armed with this impression,
namely that in the advancement of optics, there was a clear difference between
optical theory and optical practice, Camper settled in Franeker.
That Van der Bildt, in Franeker, could develop into the Netherlands’ most
productive builder of reflecting telescopes, whose products were seen qualitatively
as good as Short’s, was of course not due to Camper’s interest in the topic. There
are many reasons for this remarkable development. Yet, it is clear that at the end of
the 1740s, the conditions in Franeker under which Van de Bildt could work were
very favourable. Through Loré, not only had Van der Bildt acquired optical
expertise in Amsterdam, but in that city, he had found a market for his products.
At home in Franeker, Van der Bildt was surrounded by a number of newly
appointed professors with interest and good contacts. Although Loré, his initial
mentor, died in 1744, Van der Bildt had the good fortune that professors such as
König (in 1746), Allamand (in 1747), Camper (in 1749), and Brugmans (in 1755)
came to Franeker. In contrast to their predecessors, the appointed professors had
an eye for the role of experimentation in the natural sciences. A keen interest for
scientific instruments and their makers was a natural part of this.89 Whereas, in
1745, a small wooden cabinet was sufficient for the storage of all of the scientific
instruments in the university, in 1754 a large laboratory with an assistant was
needed to house all of the instruments acquired.90 Van der Bildt, who was
appointed as keeper of the instruments, accordingly gained a basic income, as
a result of which less heavy demands were placed upon his entrepreneurial
skills.91
5.4. Leeuwarden and Groningen: the influence of the Stadholder’s court
As an entrepreneur, Van der Bildt had previously received crucial support. In
about 1745, Samuel König introduced him to the Stadholder’s court in Leeuwarden.
At the court, König gave lectures and demonstrations on experimental physics, and
Van der Bildt assisted with these experiments. This introduction gave Van der Bildt
the personal protection of Stadholder William IV. According to a letter by König,
he had recommended Van der Bildt to the Prince of Orange ‘because he is a poor
boy, with a lot of genius, who at a day in the future can make excellent pieces of
work on everything on which he tries to make an application’.92 Following this
recommendation, the Stadholder ordered a pneumatic pump and several telescopes
from Van der Bildt. Such an order was not an incidental matter. The scientific
88
Th. Nuyens, Camper’s Travel Journals. Opuscula Selecta Neerlandicorum De Arte Medica, XV,
Amsterdam, 1939, 72–3; 88–93; 162–3.
89
In 1748, J. N. S. Allamand, at that time professor at Franeker, visited several London instrumentmakers, including Harrisson, Graham, and Short. See J. N. S. Allamand to W. Bentinck van Rhoon,
August 1748 (British Library, Egerton Papers 1745, folio 596 and 616). In 1749, Allamand was appointed
at Leiden University.
90
S. H. M. Galama, Het Wijsgerig onderwijs aan de Hogeschool te Franeker, 1585–1811 (Franeker,
1954), 154.
91
In 1748, Van der Bildt was appointed ‘keeper of the clock’ of the Franeker University. In 1754, this
appointment was extended to ‘Keeper and repairer of the physical instruments’. Maria Rooseboom,
Bijdrage tot de geschiedenis der instrumentmakerskunst in de Noordelijke Nederlanden tot omstreeks 1840
(Leiden, 1950).
92
S. König to J. van Musschenbroek, 22 May 1746 (Museum Boerhaave, Leiden, Van
Musschenbroek Archive 251-c).
The Reflecting Telescope in the Netherlands
431
interests of the Frisian Stadholder William IV are well documented.93 He was involved
in the development of a new theodolite, and his cabinet of scientific instruments
contained products from the best instrument-makers in Europe.94 When the English
telescope-builder, Short, reported to the Royal Society on a newly invented telescopic
foot with equatorial mounting, it transpired that one of the three extant examples
of this valuable ‘portable observatory’ had been delivered to the Prince of Orange.95 It
is scarcely a matter of chance that Short’s equatorial telescope mounting was
imitated at about this time in the northern Netherlands. It is probable that the
telescope in question, which is now part of the collection of the Boerhaave Museum
in Leiden, is inspired by the Short reflector in the Stadholder’s cabinet of scientific
instruments at the Prinsenhof in Leeuwarden. The signature reveals that this
instrument is a joint product from the Groningen instrument-maker, Gerrit
Cramer, and the Frisian telescope-builder, Van der Bildt. These data fit in neatly
with the fact that prior to 1747, William IV was only Stadholder of Friesland and
Groningen.96 At that time, stimulating the education of local instrument-makers
was a deliberate policy of the Prince. When, in 1746, the Leiden instrument-maker,
Jan van Musschenbroek, enquired to Samuel König as to why the Frisian Court
had not placed an order for an air pump with him, König had to tell him that the
Prince favoured giving talented persons from the Northern Provinces, ‘whose
genius and diligence had been noted’, the chance to develop themselves.97 Van der
Bildt certainly benefited from this court policy, even though he was not the
only one to do so. The aforementioned Cramer from Groningen provided the
Stadholder with a luxurious microscope. The instrument-maker, Wytze Foppes,
from Leeuwarden was another ‘man of the province’ whose ‘genius’ had been
brought to the attention of the Frisian Court. A surveying instrument made by him
was acquired for the Stadholder’s cabinet, whilst a second example was ordered as a
gift for the English Royal Society. However, after the unexpected death of William
IV in 1751, the destination of this gift was changed, and on behalf of the Prince’s
widow, the instrument was offered to the University of Leiden.98 In the meantime,
93
The Frisian Stadholder Prince William IV (1711–1751) had married the English Princess Ann of
Hannover (1709–1759). When, in 1731, he stayed in London for the marriage, William attended lessons of
the Newtonian popularizer, John Theophilus Desaguliers (1683–1744). Upon returning to Leeuwarden in
1736, the Prince was educated in Mathematics and Fortification by the Franeker University professors, Loré
and Ypey. In 1744, the Prince appointed the Swiss physicist Samuel König as his adviser in scientific affairs.
When, in 1748, the office of ‘Stadholder’ was restored in the entire Dutch Republic, the court moved to The
Hague. Then, König moved with the Princes’ family. His scientific demonstrations at The Hague are recorded
in a manuscript, Leçons de Physique de Mr. le Prof. König qu’il a donne a la Haye, 1751–52 (Univ. Libr. A, ms
X.B.1). After König’s death, in 1758, his cabinet of scientific instruments (578 pieces, including ‘a very nice
telescope’ by Van der Bildt) was auctioned at The Hague. See Catalogue d’une tres belle collection des
instruments, de mathematique, de physique, &c. Deslaissez par Feu, Monsieur Samuel König, Bibliothecaire de
S.A.S. Monseigneur le Prince Stadthouder (La Haye, Pierre Gosse Jr. and Nicolaas van Daalen, 1758), 26 pp.
(Univ. Libr. Amsterdam). Note added in proofs: see also at length, Ph. Breuker, ‘Friese Hofeultuur,’ De Vrije
Fries, 83 (2003), 75–116.
94
P. R. de Clercq, ‘Science at Court: the Eighteenth-Century Cabinet of Scientific Instruments and
Models of the Dutch Stadholders’, Annals of Science, 45 (1988), 113–52.
95
Bryden (note 76), 21.
96
Gregorian telescope on a parallactic mounting, signed GERRIT CRAMER, GRONINGEN FECIT.
During a recent restoration, it appeared that the large mirror of this telescope was made (and signed) by
Van der Bildt. See Engberts (note 29), 29–31.
97
Samuel König to Jan van Musschenbroek, 22 May 1746 (Van Musschenbroek Archive, inventory
no. 251-c, Museum Boerhaave, Leiden).
98
The instrument is currently in Museum Boerhaave, Leiden. See P. de Clercq, ‘A Princely Piece from
Friesland. The ‘‘Trigonometrical Instrument’’ of Wytze Foppes’, Bulletin of the Scientific Instrument
Society, no. 47 (1995), 14–16.
432
Figure 4.
Huib J. Zuidervaart
Reflecting telescope made by Gerrit Cramer of Groningen with mirror by Jan
van der Bildt of Franeker (Museum Boerhaave, Leiden).
however, the court’s policy had worked. Cramer, Van der Bildt, and Foppes would
remain employed as scientific instrument-makers for the rest of their lives.99
Equally, the financial support of the Frisian government to Foppes’ observation of
99
Gerrit Stevens Cramer (À 1755) lived in Groningen. His name appears on the subscription list for
Smith’s Volkomen samenstel der Optica (1751). Other instruments made by him include: a large sandstone
The Reflecting Telescope in the Netherlands
433
the transit of Venus in 1761 may be attributed to the influence of this local court
culture. The Province of Friesland was the only authority in the Netherlands to
support this astronomically important event. By giving Foppes a grant, the Frisian
authorities placed themselves on an equal footing with the Royal governments of
England, France, Sweden, and Russia, who also supported astronomical expeditions for the observations of the Venus transit.100
Initially, Van der Bildt was also employed as a general instrument-maker. From
König’s correspondence, it is apparent that Van der Bildt had already constructed
an air pump in 1743 for the Franeker professor, Du Bois. Later he would also make
magnetic equipment for his successor, Brugmans, this to the satisfaction of
Brugmans, who praised Van der Bildt as an ‘astute artisan’, who could make
instruments of such quality, ‘that one could not expect of another instrumentmaker’.101 Despite this laudation, Van der Bildt made a clear choice to specialize in
the production of reflecting telescopes, just as Short had done in England. This
intention becomes clear from the earlier cited letter of Koenig of May 1746. In this,
König wrote: ‘in his work Van der Bildt absolutely wants to specialize himself in
Reflecting Telescopes. He doesn’t want to make other instruments’. It was thanks
to this specialization that Van der Bildt could obtain such outstanding results. The
mirror he supplied to the Leiden Observatory in 1750 to replace the mirror in the
eight-foot reflector from Hearne that had become dull was acclaimed by Professor
Lulofs to be of ‘unparalleled’ quality.102 At about the same time, Short also
supplied a replacement mirror, but when the Swedish astronomer, Ferrner,
compared them in 1759, he had to conclude that although both mirrors could be
used in the same tube and arrangement, Short’s mirror ‘was less clear than the
other’ and ‘by quite a long way’ did not look as good as the one made by Van der
Bildt.103
Around 1750, it was clear that the reflecting telescope had developed into such
a success that at one of the first meetings of the Hollandsche Maatschappij
der Wetenschappen (the Holland Society of Sciences) at Haarlem, it could be
established that the ‘refracting telescopes with long focal length were now
sundial, erected in 1731 in the garden of the Prinsenhof (then the Groningen residence of the FrisianGroningen stadholder); a sundial for the Groningen Martinikerk (1748); a lens telescope (Louwman
collection, Wassenaar); and two very finely constructed compound microscopes (Museum Boerhaave,
Leiden). The instrument-maker, Wytze Foppes (1707–1778), worked in Leeuwarden from 1751 onwards.
In 1753, he proclaimed himself to be a ‘geometric telescope builder’. He did indeed make some reflecting
telescopes. For a catalogue of the scientific instruments made by Foppes, see Zuidervaart (note 81),
177–86.
100
Zuidervaart (note 27), 372–73. In 1765, after the death of the Stadholder’s mother, the Frisian
Court at Leeuwarden was dismantled. With the disappearance of this princely stronghold, the provincial
support for scientific projects gradually diminished. As a result, the Venus transit of 1769 failed to attract
any attention.
101
Antonius Brugmans, Tentamina philosophica de materia magnetica (Franequerae, 1765). Translated
in the German language as Philosophische Versuche über die magnetische materie und deren Wirkung in
Eisen und Magnet (Leipzig, 1784), 256.
102
Johan Lulofs to Dirk Klinkenberg, 9 May 1751 (Rijksarchief Noord-Holland, Haarlem, Archives
Kon. Ned. Instituut, no. 32).
103
Kernkamp (note 47), 470–1. Telescope mirrors were often replaced. For instance, in 1789, in the
catalogue of the Amsterdam Ebeling collection, a Gregorian reflecting telescope made by Dollond is
mentioned, from which the original mirrors were replaced by others made by ‘J. van der Bildt, the elder’.
The catalogue claims that the instrument was ‘very much improved by this operation’. Cf. Naamlijst …
van Wis- en Natuurkundige Werktuigen, bijeen verzameld door Mr. E. Ebeling (Amsterdam, N. C.
Gravius, 1789), nos. 417 and 418 (Libr. Museum Boerhaave, Leiden).
434
Huib J. Zuidervaart
completely obsolete’.104 By then, Van der Bildt’s reputation as a skilled telescopebuilder was firmly established. In Haarlem, at any rate, it was proclaimed that the
telescopes sold in Franeker were not only ‘better fabricated’ than English telescopes, but in comparison were ‘very cheap’.105
6. Dutch reactions to the achromatic telescope
Van der Bildt and his Frisian followers are known to have built only reflecting
telescopes. In light of the emergence of the achromatic telescope after 1760, this is
certainly somewhat peculiar. The Amsterdam instrument-makers, Van Deijl, for
instance, developed themselves from about 1765 into producers of good-quality
achromatic telescopes. If this could happen in Amsterdam, then why not in
Friesland? Why did developments in Friesland remain so one-sided?
The achromatic telescope was a spectacular improvement on the refractor
telescope, patented in 1758 by the English instrument-maker, John Dollond.
Despite the protection offered by this patent, Dollond still preferred to say as little
as possible about his telescopes.106 Therefore, the announcement of this spectacular
instrumental development in the Dutch press was accompanied by a call to the
readers to consider the problem of ‘the inner workings of this telescope’ and to
publicly announce any suggestions as to its working.107
6.1. Bley and Van Deijl
The Amsterdam brass-caster, Carl Ulrich Bley, devoted himself to this calling.
He was not unknown amongst Amsterdam’s optical amateurs. According to
Hennert, he was the ‘artisan’ who had cast the metal for the mirror of Van de
Wall’s telescope. The same Bley carried out pioneering work in the development of
the Dutch version of the achromatic telescope. In 1761, he found the solution to the
puzzle of how Dollond’s telescope operated. Bley published his findings in 1765 in
the Verhandelingen van de Hollandsche Maatschappy der Wetenschappen.108 He had
been able to imitate to Dollond’s results due to a happy combination of
experiments with lenses made of different sorts of glass and some mathematical
reasoning. In these experiments, Bley had received assistance from the Amsterdam
104
Anonymous comment on a proposal by Louis Wurstenberguer from Kleve (now in Germany) on
the production of ‘all kinds of telescopic glasses and mirrors’ (Rijksarchief Noord-Holland, Haarlem,
Archives of the Hollandsche Maatschappij van Wetenschappen, correspondence of 1752).
105
Van der Bildt’s early reputation is reflected in the announcement of the auction of the instrument
collection of Anthony van Maurick, held at Amsterdam in August 1760. In this auction ‘two telescopes
of the famous Van der Bilt’ were sold [Van der Krogt (note 42), no. 1161].
106
See: R. Willach, ‘New Light on the Invention of the Achromatic Telescope Objective’, Notes and
Records of the Royal Society of London, 50 (1996), 195–210; J. A. Bennett, ‘Peter Dollond Answers Jesse
Ramsden’, Sphaera. The Newsletter of the Museum of the History of Science, Oxford 8 (Autumn 1998), 4–
5 and Richard Sorrenson, ‘Dollond & Son’s Pursuit of Achromaticity, 1758–1789’, History of Science, 39
(2001), 31–55.
107
In 1760, the original English article on Dollonds invention (from The Gentleman’s Magazine of
1759) was translated into Dutch by Martinus Houttuyn, in Uitgezogte Verhandelingen uit de nieuwste
werken van de Societeiten der Wetenschappen in Europa, 5 (Amsterdam, 1760), 554–63.
108
C. U. Bley, ‘Verhandeling over de hoeveelheid der refractie en kleuren van het licht door glas
gaande. Alsmeede op wat wyze de kleuren door lensvormige glaazen voortgebragt, kunnen weggenoomen
worden’, Verhandelingen uitgegeven door de Hollandsche Maatschappij der Wetenschappen, 8 (1765), 417–
63 (1 plate). Bleij’s manuscript was evaluated by the Leiden professor, Johan Lulofs, and the Amsterdam
mathematician, Cornelis Douwes (Rijksarchief Noord-Holland, Haarlem, Archives of the Hollandsche
Maatschappij van Wetenschappen, notulen, I, fol. 390).
The Reflecting Telescope in the Netherlands
435
‘artisan and lens grinder’, Jan van Deijl. Together, they had built a prototype
achromatic telescope. However, this ‘optical machine’ was not yet fully functional.
They continued to experience some inconvenience from chromatic and spherical
aberrations. But according to Bley, this was mainly because ‘the proportions of the
lenses were somewhat different than required’. The development of this Dutch
prototype of the achromatic telescope had considerable consequences for Jan van
Deijl. In the following decade, this instrument-maker (together with his son
Harmanus) established a firm that would develop rapidly into the Dutch
counterpart of the English company Dollond. In 1762, the Van Deijls delivered
their first achromatic telescope, and two years later, they even managed to improve
the original design.109
6.2. Van Musschenbroek
Shortly before his death, the Leiden professor, Petrus van Musschenbroek,
comprehensively studied the functioning of the achromatic telescope. Van
Musschenbroek, who died in the autumn of 1761, left behind a private instrument
cabinet, which, after his death, was publicly auctioned in Leiden. In the auction
catalogue, there were several objects of note, including ‘a prism made up of 3
prisms composed of different glass set in copper, serving to clarify the construction
of Doullont’s telescopes’. This demonstration model may be viewed as one of the
first attempts to illustrate the effects of Dollond’s invention for educational
purposes. Achromatic telescopes were also present in Van Musschenbroek’s
cabinet. Upon his death, he possessed two achromatic telescopes, namely ‘a
telescope of six lenses, three foot long, in a mahogany wooden tube from Dollont’,
provided with a spare objective, and a pair of ‘exquisite opera glasses from a new
invention by Doullont his new method’. Van Musschenbroek’s enthusiasiasm about
Dollond’s invention is also apparent from the last Latin edition of his physics
textbook, which was published posthumously in 1762.110
6.3. Van de Wall
At Amsterdam, the merchant and telescope-builder, Jacobus van de Wall, had
also followed the latest developments. At any rate, the Danish astronomer, Bugge,
stated in 1777: ‘Mr Van de Wall, who is now in his seventy seventh year, showed
me an excellent piece of flint glass from England. It was 9 inches in diameter and 2
inches thick, and it was completely free of veins and striae. Compared with this he
showed me a piece of crown glass, full of veins, which he had ordered from
Germany. If it had been good, he would have made a Dollond telescope of it’.111
Whether Van de Wall ever crafted such an achromatic telescope can no longer
be ascertained. Upon his death in 1782, he did, however, possess an ‘achromatic
109
The ‘improvement’ to the achromatic telescope carried out by the Van Deijl workshop was an
extension of the ocular from three to four lenses. See J. Van Zuylen, ‘Jan en Hermanus van Deijl. Een
optische werkplaats in de 18e eeuw’, Tijdschrift voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, 10 (1987), 208–28 and Maria Rooseboom, ‘Die Holländische Optiker
Jan und Harmanus van Deijl und ihre Mikroscope’, Janus, 44 (1940), 185–97. Both authors overlooked
the prominent role of Carl Ulrich Bley in the development of the Dutch version of the achromatic
telescope.
110
Collectio exquisitissima (note 29), nos. 317–318; 332. See also P. van Musschenbroek, Compendium
Physicae Experimentalis Conscriptum in Usus Academicos, (Lugdunum Batavorum [~Leiden], 1762),
335–6.
111
Pederson and Dybdahl (note 78), 65.
436
Huib J. Zuidervaart
telescope’, which, together with ‘some other telescopes, cat’s eye, mirrors and tools’,
was bequeathed to Jan van Deijl.
In his will, Van de Wall remembered also another instrument-maker with a
bequeathal, namely Adam Steitz. This leads one to suspect that this artisan would
also have carried out the necessary work for Van de Wall.112 In any case, it was
Steitz who, in 1782, took care of the transport of Van de Wall’s observatory to the
University of Leiden. Bugge, who visited Steitz in his shop in the Runstraat in
Amsterdam, described him as a ‘good mechanical genius’ who made instruments,
characterized by ‘very nice workmanship’. Steitz also had business dealings with the
Van Deijl Company. Together with the instrument-maker, J. Kampman, he
supplied them with the tripods for various achromatic telescopes. The instrument
collection at the Teylers Museum in Haarlem contains, for example, a large
achromatic telescope made by Van Deijl, the tripod of which was constructed by
Steitz and Kampman.113
6.4. Van der Bildt
In Friesland, people were equally aware of Dollond’s invention. In 1761, the
Franeker Academy had already expressed an interest in acquiring a telescope ‘with
lenses from the latest invention in England’.114 However, it seems that the Franeker
University never managed to obtain such an achromatic telescope.115 That does not
detract from the fact that the local instrument-makers would have been informed
about these developments. For example, there is the story of the young physicist,
Henricus Aeneae, who is said to have learned the art of building telescopes from
both Foppes and Van der Bildt, and who, in about 1766 in Amsterdam, personally
saw the remarkable qualities of the achromatic telescope. If this report is true—and
it would seem to originate from reliable sources—then it is unlikely that Aeneae
would have failed to report this to both of his teachers.116
Yet, why did the instrument-makers in Friesland persist with building solely
reflecting telescopes? Was the manufacture of an achromatic telescope perhaps too
difficult for Van der Bildt? This hardly seems to be plausible. Someone who is
praised for his skills by contemporaries, and who is capable of constructing mirrors
of such a finely balanced alloy that the majority of them have maintained their
reflectivity after more than two centuries, sets a standard rarely equalled by other
telescope-builders. Whoever achieved this can hardly be considered a craftsman of
112
I. H. van Eeghen, ‘Het beroep van Adam Steitz’, Maandblad Amstelodamum, 57 (1970), 177–8 (on
a brass press made by Steitz in 1758). The oldest scientific instrument made by Steitz is a solar
microscope in the collection of Museum Boerhaave, Leiden, signed A. STEITZ, 1760.
113
G. L’E.’ Turner, Van Marum’s scientific instruments in Teylers Museum, Vol. IV or Martinus van
Marum. Life and Work (Leyden, 1973), edited by R. J. Forbes, E. Lefebvre, and J. G. de Bruijn, no. 264:
achromatic telescope, signed: JAN VAN DEIJL & ZOON FECIT AMSTERDAM Ao 1781. According to
Turner, this instrument is from the Ebeling sale (note 103), nos. 392 and 393. This catalogue states that
Van Deijl made only two copies of this large type of telescope. The stand of mahogany was constructed
by Kampman, on which Steitz made a copper construction for the horizontal and vertical movement of
the telescope. An identical instrument can be found in the collection of the Utrecht University Museum,
and an identical stand is in the Museum Boerhaave, Leiden. See Engberts (note 29), 57.
114
Rijks Archief Franeker, Leeuwarden, Archives of the Franeker University, inventory no. 1 (last
page).
115
Also, in the nineteenth century, no mention is made of any achromatic telescope in the inventories
of the Franeker cabinet of scientific instruments. (Leeuwarden, Archive Rijksatheneum in Franeker).
116
Joh. Buys, ‘Rede ter nagedachtenisse van den weledelen heer Henricus Aeneae’, Algemeene Konsten Letterbode, 1811-I, 133–7. Buys was Aeneae’s colleague at Felix Meritis.
The Reflecting Telescope in the Netherlands
437
modest abilities. Therefore, it seems far more likely that Van der Bildt was
convinced of the superior quality of his own product. After all, reflecting telescopes
were already achromatic. What therefore could be gained? Furthermore, in a
reflecting telescope, the number of surfaces that needed to be ground and polished
was considerably less than in an achromatic telescope with three or four lenses.
Moreover, almost all the flint glass required for an achromatic telescope was
available only in a small size. Larger pieces necessary for building an achromatic
refractor were very difficult to acquire.117
The main problem of reflecting telescopes had always been the relatively low
light yield. This was caused by two factors: the reflective capacity of the mirror
metal and the surface of the mirrors. In response to the ‘Dollond’s telescopes’, Van
der Bildt wished to tackle both matters. In 1773, he successfully improved his
mirror alloy. Van der Bildt reported to one of his business contacts that he had
found ‘some improvement to the metal mirrors’ as a consequence of which, his
telescopes had become ‘considerably clearer’.118 Yet, his efforts to construct larger
mirrors were less successful. However, in 1767, Van der Bildt was still full of
confidence. In April of that year, he wrote to the Royal Prussian Academy of
Sciences in Berlin, stating that, in response to the reports about ‘the telescopes with
double objectives’, he had constructed a Newtonian telescope with a ‘50-inch focus’
and a 500-times magnification in diameter. According to Van der Bildt, only a
magnification of just 100 times could be obtained with an achromatic telescope, but
the glass for such a telescope was scarcely obtainable. This was no problem for Van
der Bildt, as he preferred ‘much more the reflecting telescope’. Nevertheless, he
promised his German correspondent that he would ‘really investigate what a double
lens is capable of’. In the meantime, he had already started to work on a larger
reflecting telescope with a magnification of around 1000 times. If it would please
his ‘Prussian majesty’, Van der Bildt could try to make an even larger reflecting
telescope. Van der Bildt estimated that such a telescope could have a magnification
of about 1500 times. With such an instrument, the king would be able to see objects
that ‘no human eye had ever seen’. The telescope would cost 1000 ducats, but
according to Van der Bildt, ‘if I cannot show it, I will not take a penny’.119
Indeed, the Prussian king did order such a large telescope. Van der Bildt’s
grandchildren still boasted of this story to Scheltema, Van der Bildt’s first
biographer.120 Other sources confirm that during the period 1768–1770, Van der
Bildt worked on a remarkable ‘optical machine’. However, as we will see, the
project did not work out as expected.
117
Hemsterhuis ascribed the shortage of Flint glass to the destruction of the Scottish glass factories
during the civil war between Scotland and England. [Frans Hemsterhuis to Princess Amalia de Gallitzin
(‘Diotima’), 22 and 28 July 1783] (Universitätsbibliothek Munster, Germany; Prof. M. F. Fresco at
Leiden kindly furnished me with copies of these). See also Van Zuylen (note 109), 218–20 and Gerard
L’E. Turner, ‘The Government and the English Optical Glass Industry, 1650–1850’, Annals of Science, 57
(2000), 399–414.
118
Van der Bildt to Johannes Berghuis at Delft, 22 March 1773 (Teylers Museum, Haarlem, Family
archive Van Breda).
119
Van der Bildt to Kon. Preussische Akademie der Wissenschaften, Berlin, 17 April 1767 and 24
August 1767 (Archiv Akademie der Wissenschaften, Berlin, I-XIV no 27 (courtesy of Rolf Riekher,
through Peter Louwman).
120
Scheltema (note 83), 241–2.
438
Huib J. Zuidervaart
A
B
Figure 5.
Signatures on reflecting telescopes made by Jan Van der Bildt of Franeker and
Wytze Foppes of Leeuwarden (Collection Louwman, Wassenaar).
The Reflecting Telescope in the Netherlands
439
6.5. Industrial espionage ordered by Frans Hemsterhuis
It was probably Petrus Camper who informed his childhood friend, Frans
Hemsterhuis, about Van der Bildt’s project. In contrast to Camper, Hemsterhuis’
interest in optics and optical instruments had never diminished. For example, the
connection between Hemsterhuis and the Amsterdam instrument-maker’s company,
Van Deijl, was so close that in 1767, a group of visiting French astronomers took
him to be their company director.121 The fact that, in 1783, Hemsterhuis himself
claimed that all of the achromatic telescopes made by the Van Deijl Company had
passed through his hands does in any case indicate a special relationship with these
Amsterdam instrument-makers.122 Camper enjoyed a good relationship with Van
der Bildt. Camper’s earlier interest in optics guaranteed a natural contact with the
instrument-maker. The rumour that, in 1756, Van der Bildt had spied upon him
with a telescope when he was courting his future wife was something Camper never
seems to have held against him.123 Camper was also well known amongst the
optical amateurs in Amsterdam.124 From 1756 to 1761, he had lived in the capital
when he was professor at the Athenaeum Illustre. After 1761, he once again lived at
his country estate near Franeker, where, as a citizen without profession, he involved
himself with all kinds of scientific projects. However, because of the acceptance of a
new professorship, Camper moved to Groningen in 1768. As a result of this, he
could no longer keep Hemsterhuis informed about Van der Bildt’s progress. What
was to be done? Although, from time to time, Hemsterhuis exchanged some letters
with Van der Bildt, it was clear that the somewhat dour telescope-maker was not
being completely open with him. Therefore, Hemsterhuis recruited a young student
at the Franeker Academy and encouraged him to become friendly with Van der
Bildt. Thanks to this ‘industrial espionage’, Hemsterhuis was still able to obtain the
necessary details. The chosen accomplice was squire Hans Willem van Aylva (1751–
1827), the son of a Frisian connection. The young Van Aylva, who clearly enjoyed a
position of trust with the Dutch philosopher, was more than happy to help him. His
letter dating from August 1768 was almost entirely devoted to Van der Bildt and
his affairs. And although, unfortunately, only Hemsterhuis’ answers have survived, it
is clear that between 1768 and 1770, things did not go well for Van der Bildt.125
First of all, at a personal level, some trouble was brewing between Van der Bildt
and his eldest son, Jan van der Bildt junior. The precise nature of the problems is
not clear, but the designation ‘his unworthy son’, which Hemsterhuis ascribed to
Van der Bildt junior, points to matters of a grave nature. Scheltema also refers to
‘many trials and tribulations’ which Van der Bildt had suffered at the hands of his
121
Journal of A. G. Pingré (1767), Bibliothèque Sainte-Geneviève, Paris, Mss.Pingré, no. 1805, fol. 27:
account of the visit to W. Bentinck van Rhoon on his estate ‘Zorgvliet’ near The Hague.
122
Hemsterhuis to De Gallitzin, 22 July 1783 (note 116). See also Brummel (note 84), 34.
123
For this anecdote, see J. Schuller tot Peursum-Meijer and W.R.H. Koops (eds.), Petrus Camper
(1722–1789). Onderzoeker van nature (Groningen, 1989), 104.
124
Camper’s relation with Feyt was established during his university years; Camper’s correspondence
with Cornelis Ploos van Amstel started in 1755, and his relationship with the Van de Wall family is
apparent from the last will of Johannes van de Wall, who, after his death, donated a large sum of money
to the three children of Camper (Municipal Archives Amsterdam, NA 14691, nos. 115, 121 and no. 200
(June and October 1784)). See also R. A. B. Oosterhuis, ‘Petrus Camper en Amsterdam. De
wetenschappelijke loopbaan van Camper en de wederzijdse culturele betrekkingen van 1755 tot 1761’,
Geneeskundige gids, 17 (April 1939), 403–19.
125
J. Van Sluis, ‘Hemsterhuis en de familie-Van Aylva. Tekstuitgave van een [Franstalige]
correspondentie’ [Geschiedenis van de Wijsbegeerte in Nederland. Documentatieblad van de Werkgroep
‘Sassen’, 2 (1991), 71–88]. Citations are from pp. 79, 82, 84, and 85.
440
Huib J. Zuidervaart
two sons, Jan junior and Lubbertus. Indeed, Scheltema suggests that both sons had
dissociated themselves from their father and were making reflecting telescopes of an
inferior quality under their own names.126 Whatever the problems were, it drove the
elderly Van der Bildt into considering leaving Friesland. A new place to establish
himself had already been chosen: Haarlem, birthplace of the Holland Society of
Sciences. In his letter to Aylva, Hemsterhuis promised to do his best to pave the
way for Van der Bildt. For safety’s sake, he advised his Frisian friend to ascertain
whether Van der Bildt would not be taking too great a financial risk by making
such a move. Of course, by moving to Holland, Van der Bildt would forfeit the
annual stipend he received from the university and the city council of Franeker.
Hemsterhuis’ research of the market produced an unfavourable prognosis. At the
end of 1769, he had to advise Van der Bildt to stay in Franeker. Meanwhile, the
‘large project’ that Van der Bildt was secretly working on was also discussed in the
correspondence. Hemsterhuis, who clearly was not aware of the highly placed
Prussian client, showed himself to be highly interested in Van der Bildt’s product.
He informed Van Aylva that he would like to have such a telescope for himself. For
such a ‘great machine’, he was prepared to spend 1500–2000 guilders. Who else
would be willing to pay Van der Bildt such a large sum of money? Hemsterhuis did
not know any amateur, not even the Prince of Orange, who would spend such an
amount. This was a very different matter in France and England: over there,
Hemsterhuis knew of princes and dukes who took pride in providing a talented
‘artisan’ with a handsome annual income. But in the Dutch Republic? According to
Hemsterhuis, people there loved money more than quality and beauty. Nevertheless, as soon as Van der Bildt’s ‘admirable machine’ would be ready, Van Aylva
had to seize the initiative. He immediately had to take a look at Saturn.127
Hemsterhuis envied the young Frisian’s opportunity: ‘as you will be one of the first
people … who will see the true nature of this amazing planet, which is eighty times
bigger [in surface] than that which we inhabit’. Van Aylva was instructed to send a
detailed report about the things he saw.
However, in the early spring of 1769, it appeared that the project had scarcely
made any progress. Although Hemsterhuis had again made direct contact with Van
der Bildt, who in a letter had promised much concerning the new telescope, the
possibility of observations remained a long way off. When, in a subsequent letter,
Van der Bildt made no mention whatsoever of the large telescope, Hemsterhuis
commissioned Van Aylva in no uncertain terms to spy: ‘Go to this man whenever
your study allows you to, so that I know the state of affairs with respect to this
machine, as he has said nothing about it in his letters’. Scarcely two weeks later,
126
Scheltema (note 83), 240. Indeed, some telescopes exist which are signed JAN VAN DER BILDT
JUNIOR and LUBBERTUS VAN DER BILDT. Little is known about the life of these sons of Van der
Bildt. The oldest son, Jan van der Bildt (1736–c.1780), matriculated as a student to Franeker University
in 1755. According to Rooseboom, he married in 1762, after which he was convicted on several occasions
for fighting and purgery. The other son, Lubbertus van der Bildt (1738–c.1780), is mentioned in 1767 as a
microscope-maker. Both sons worked until about 1780. See Rooseboom (note 91), 30–4, and S. J.
Fockema Andreae and Th. J. Meijer, Album studiosorum academiae Franekerensis (1968), no. 12917.
127
An observation of Saturn’s rings was commonly viewed as a means of testing a telescope’s quality.
In 1774, Van der Bildt carried out some observations together with his grandson Bauke Eisma (van der
Bildt) using a Gregorian telescope of ‘19 inches focus’ and a Cassegrain telescope of ‘48 inch focus’. In
1778, he did the same with professor Van Swinden, who reported this observation to the French
astronomer, J. de Lalande. Cf. Van der Bilt (note 83), 5, and University Library Leiden, BPL 755, J. H.
van Swinden to J. J. de Lalande, 9 September 1778.
The Reflecting Telescope in the Netherlands
441
Hemsterhuis impatiently enquired about the ‘optical affaires’. Eventually, Van
Aylva acquitted himself of the assigned task. In November, Hemsterhuis thanked
him for his efforts. But he urged Van Aylva to continue with his spying activities,
but without forcing his company upon Van der Bildt: ‘For pity’s sake do what I
wrote you about, but please do use a bit of discretion!’. At the end of December,
Hemsterhuis again expressed his gratitude for Van Aylva’s reports about the ‘large
machine’ in which he was so interested. During the course of 1770, we also learn
why. In a moment of intimacy, Hemsterhuis reveals his plans for Van der Bildt’s
telescope. He emphasizes the need to keep these intentions hidden from Van der
Bildt. Supposing that Van der Bildt was indeed prepared to place this ‘unequalled
machine’ at Hemsterhuis’ disposal, he would install the instrument in Warmond, a
Dutch village near Leiden. There, Hemsterhuis had a house in mind for the
research he wanted to carry out with this amazing instrument.
Warmond was not chosen by chance. Here lived Hemsterhuis’ tutor in
optics, Hendrik Feyt. Together with him and the instrument-makers Van Deijl,
Hemsterhuis wished to try to improve Van der Bildt’s telescope in such a way that
eventually, ‘the most astonishing optical machine would arise which had ever been
seen anywhere’. Hemsterhuis does not describe the nature of the intended
modifications. In view of the involvement of father and son Van Deijl it is logical to
assume that Hemsterhuis wished to equip Van der Bildt’s large telescope with an
achromatic eyepiece.
Towards the end of 1770, Hemsterhuis became impatient because, all things
being considered, it had taken long enough. Because of the rent he had to pay for
the house in Warmond, Hemsterhuis had to know where he stood with Van der
Bildt. Otherwise, he would divert his attention towards an apparatus shortly to be
received from London. This instrument would scarcely be less astonishing than Van
der Bildt’s telescope. With this designation, Hemsterhuis probably meant an
achromatic (binocular?) telescope made by Dollond. In any case, everything
indicates that after 1770, Hemsterhuis fully devoted himself to the construction of a
binocular achromatic telescope. When the Swede, Bjornstahl, visited the Netherlands in 1773, he noted the following about Hemsterhuis in his travel journal: ‘He is
a mathematician and astronomer; as an optician he has invented telescopes of a
new construction’.128 With this, Bjornstahl alluded to the binocular achromatic
telescopes produced by the Van Deijl company in very small quantities.129 It seems
that Hemsterhuis had indeed contributed the necessary knowledge to this
instrument. We learn about the precise nature of his contribution from an
encyclopaedia edited in Leeuwarden in 1778: ‘The famous and shrewd Mr F.
Hemsterhuis, … has again breathed new life into the telescopes of Galileo and has
so improved them, that one cannot behold them without being awe-struck’. Also
from the same time is the report that ‘Mr. Hemsterhuis in The Hague … by means
of a binocular telescope is carrying out important observations concerning the
diameters of the fixed stars’.130
128
Cited after Petry (note 59), 219.
The only known copy of this telescope (dated 1789) can be found in the Teylers Museum,
Haarlem. See Turner (note 113), 294–6.
130
Noël Chomel, Algemeen Huishoudelijk-, Natuur-, Zedekundig- en Konstwoordenboek [General
Household, Nature, Moral and Arts Dictionary]. Second edition improved by J. A. de Chalmot, vol. 7
(Leiden/Leeuwarden, 1778), 3630 (lemma ‘telescope’, probably written by Petrus Camper). See also
Gijsbert Stapert to Jacob Van Breda, 12 February 1774 (Family archive Van Breda, Teylers Museum,
Haarlem).
129
442
Huib J. Zuidervaart
In spite of his success with the binocular telescope, Hemsterhuis clearly had to
abandon his plans with Van der Bildt’s reflecting telescope. Neither he, nor
Frederick the Great, ever laid hands on the large telescope promised by Van der
Bildt. Van der Bildt’s grandson and successor, Bauke Eisma van der Bildt, later
spread the story that Van der Bildt had never delivered his telescope to the King of
Prussia because of a conflict with the intermediary in Amsterdam, through whom
the order was placed.131 A more likely scenario is that Van der Bildt never
succeeded in making a satisfactory parabolic mirror. Whereas, for small telescopic
mirrors, the difference between the spherical form and a paraboloid stays within the
limits of tolerance, this parabolic excess is no longer acceptable for mirrors with a
larger diameter. Understandably, Van der Bildt did not wish to put his reputation
at risk, and he therefore never relinquished the apparatus. According to his first
biographer, Scheltema, the large telescope was still in the possession of the
grandson, Bauke Eisma van der Bildt, in 1823. This grandson was also a telescopebuilder, so he probably also guarded his grandfather’s reputation, as, after this
moment, nothing further is known about this large Frisian telescope.132
And Hemsterhuis? What he eventually thought about the qualities of a
reflecting telescope can be learned from his reactions to the discoveries of Herschel
in the 1780s.133 After having studied optics for more than 50 years, a subject on
which Hemsterhuis had spent more money than he had intended, he was convinced
that the achromatic telescopes of Van Deijl were the best that could be made. He
already had an essay ready for the press in which he demonstrated the ‘singularity,
profoundness and excellence’ of these telescopes. However, this essay was never
printed, because he had given the manuscript to Prince Wenceslaus of Liechtenstein,
who never returned it. So, Hemsterhuis took the jubilant reports about the
achievements of Herschel’s reflecting telescopes with a grain of salt. The report that
the Göttingen observatory had a Herschel telescope with a purported magnification
of 6000 elicited the response from Hemsterhuis that if such a reflecting telescope
existed, he would personally guarantee that it would be of a lower quality than the
largest achromatic telescope made by Van Deijl. After all these years, Hemsterhuis
no longer believed in the feasibility of a large reflecting telescope. According to him,
the light-gathering power of small mirrors was too low, whereas large mirrors—as
had been shown—became malformed under their own weight. Upon his death in
1791, it was revealed that Hemsterhuis possessed only one old reflecting telescope of
12-inch focal length, not made by Van der Bildt, but constructed by the English
131
Scheltema (note 83), 242. This was probably Egbert Buys, counsellor of the Courts of Poland and
Prussia at Amsterdam. Buys was also the main editor of the Algemeene Spectator (1748); De Hollandsche
Wysgeer (1759–1763) and the Nieuw en volkomen woordenboek van konsten en wetenschappen (1769–
1778). Cf. P. J. Buijnsters, Spectatoriale geschriften (Utrecht, 1991).
132
According to W. B. S. Boeles, Frieslands Hoogeschool en het Rijksatheneum te Franeker, vol. 1
(Leeuwarden, 1878), 424, the large telescope was bought in 1831 by the ‘Rijks Atheneum’ at Franeker
from the estate of the late Bauke Eisma van der Bildt. However, the instrument is not mentioned in the
1843 inventory of the instruments of the Atheneum, so this statement seems to be uncertain. Enquiries as
to the fate of the telescope, made in 1939 by Van der Bilt, were in vain. See Van der Bilt (note 83), 10.
According to Scheltema (note 83), 239, the largest telescope Van der Bildt ever sold was in the cabinet of
the Amsterdam merchant, Ernestus Ebeling. This 7-foot telescope is mentioned in the auction sale
catalogue of 1789 (note 103), as number 420. It had a Gregorian and a Cassegrain outfit, very rare for a
Van der Bildt telescope. As early as 1823, the destiny of this telescope was unknown. A similar, but
smaller, 5-foot telescope by Van der Bildt, also with both a Gregorian and a Cassegrain outfit, was
acquired in 1984 by the Teylers Museum in Haarlem. See G. L’E. Turner, ‘Van der Bildt telescope in
Teylers Museum’, in Bulletin of the Scientific Instrument Society, no. 9 (1986), 13–14.
133
Hemsterhuis to De Gallitzin, 10 August 1786 and 16 October 1787 (note 117).
The Reflecting Telescope in the Netherlands
443
instrument-maker, George Sterrop (À 1755). Yet, he possessed at least 10
achromatic telescopes: five made by Dollond (including two binocular telescopes),
four made by Van Deijl, and one made by the English instrument-maker, Gilbert.
He apparently no longer possessed an example of his own design for a binocular
telescope: perhaps he had generously lent this instrument to an associate ‘who
enjoyed himself tremendously with it’.134
7. The end of the Dutch production of reflecting telescopes
7.1. Van de Wall’s telescope at the Leiden Observatory
Owing to the failure of Van der Bildt’s project, in 1782 Van der Wall’s telescope
was still the largest reflecting telescope available in the Netherlands. In view of the
fact that the mirror of the university’s 8-foot Hearne telescope (which had been
refurbished in 1750 by Van der Bildt) had perished in 1769,135 the legacy of such an
‘outstanding piece’ was seen as particularly fortunate for Leiden’s University. The
fact that the instrument was already several decades old was clearly not found to be
objectionable. In light of the contemporary reports about the exceptional capabilities of Herschel’s new reflecting telescopes, this may be termed strange at the very
least.136 It illustrates the fact that the prominent position occupied by the University
of Leiden at the start of the eighteenth century in Europe had in the meantime
unmistakably waned. Whereas, in 1734, with the arrival of Hearne’s telescope,
‘s-Gravesande had equipped the university with a telescope which then represented
the ‘state of the art’, little remained of this leading position just half a century later.
Dionysus van de Wijnpersse, then professor of Astronomy was indeed no ‘sGravesande. In many respects, he failed to live up to his predecessor. Van de
Wijnpersse scarcely made observations and showed himself to be entirely satisfied
with the telescope from Amsterdam. Van de Wall’s instrument-maker, Steitz, was
ordered to bring the instrument and the observatory building to Leiden, where
the telescope would be provisionally placed in one of the university buildings. Van
de Wijnpersse promised to search for a proper location to rebuild the observatory.
In the mean time, Van de Wall’s observatory was dismantled and stored.
Just as Van de Wall’s telescope had scarcely served the cause of astronomy in
Amsterdam,137 it would also not enjoy any fame in Leiden. The wooden parts of
Van de Wall’s observatory languished in the attic of the town carpenter, and the
telescope was never set up properly. It is questionable whether any observations
were ever made with it. The astronomer, Kaiser, who in 1826 came across Van de
Wall’s disused telescope at the Leiden observatory, reported later that the
instrument ‘which was very well crafted’ was set up in a long room on the ground
floor.138 Through a hatch, only a small part of the western sky could be observed.
134
Pars Bibliothecae Hemsterhusianae (Hagae Com., 1791), 147–9.
J. N. S. Allamand to François Cesar le Tellier, Marquis de Courtanvaux, 4 July 1769 (Académies
des Sciences, Paris, dossiers personelles, s.v. ‘Allamand’).
136
Herschel started with the construction of reflecting telescopes in 1773. He received international
acclaim after the discovery of Uranus in 1781. See J. A. Bennet, ‘‘‘On the power of penetrating into
space’’: The telescopes of William Herschel’, Journal for the History of Astronomy, 7 (1976), 75–108.
137
The only known observation with the Van de Wall telescope is recorded by Bugge. Van de Wall was said
‘to have observed that the rings of Saturn decline towards the edges and get thicker towards Saturn. And
that Saturn was full of circles parallel to themselves and to the ring’. Pederson and Dybdahl (note 78), 63.
138
F. Kaiser, ‘Geschichte der Astronomie und der Sternwarte an der Universität in Leiden’, Annalen
der Sternwarte in Leiden, 1 (1868), I–LII, i.h.b. xiv en LIV. See also F. Kaiser, Het observatorium te
Leiden (Leiden, 1838).
135
444
Huib J. Zuidervaart
Yet, by then, the instrument was not even allowed to fulfil this modest task. In
Kaiser’s time, the primary mirror had become dull, as a result of which,
observations were no longer possible. As Kaiser makes no mention of the three
spare mirrors still mentioned in the 1798 inventory of the Leiden observatory, we
may assume that these had disappeared.139 According to Kaiser, his predecessor,
Van de Wijnpersse, had allowed astronomy to become completely extinct at Leiden,
as a result of which ‘the earlier instruments’ such as ‘the outstanding telescope of
Mr Van de Wall bequeathed to the university’ had produced ‘not even the slightest
of fruits’.
7.2. New technological developments
Yet, although these Dutch developments contrast wryly with the exceptional
achievements of Herschel’s reflecting telescopes in England at about the same time,
things were to become much worse. Seen from an economic viewpoint, the once
powerful Dutch Republic was clearly on the wane, and this was also noticeable in
the scientific developments. Although there was some interest for Herschel and his
telescopes, this interest was scarcely of any consequence. Not everyone believed the
reports that circulated. A few Dutch scholars, however, went to assess the situation
for themselves, such as Petrus Camper, who visited Herschel in 1785, and Martinus
van Marum, who did the same in 1790.140 Deeply impressed by what he had
witnessed with his own eyes, Van Marum acquired in that same year a 7-foot
Herschel telescope for the Teyler Foundation. Other new acquisitions for Teyler
were: in 1789 a large Dollond reflector with heliometer, in 1791 a portable
equatorial telescope made by Ramsden, and in 1792 an extremely rare binocular
achromatic telescope made by Van Deijl. This was probably the last
binocular telescope made according to Hemsterhuis’ design. A complete novelty
was the acquisition in 1794 of a small reflecting telescope with a platinum mirror.
This telescope had been made in London by Dollond and was furnished with a
mirror supplied by the French abbé Rochon, after an idea that was first
implemented in 1785.141 Yet Dutch astronomy was hardly served by these excellent
instruments. For the many-sided Van Marum, astronomy was not a main interest,
and others were not permitted to use the instruments in Teyler’s excellent
collection.142
7.3. Frisian ‘Farmer professors’
Meanwhile, hardly any innovation had taken place within the Dutch telescope
industry. Around 1800 reflecting telescopes were made almost exclusively by
Frisians (see table 1), according to the tried and tested model of Van der Bildt. This
‘dean’ of the Dutch telescope-makers had died in 1791. In his 40-year career, Van
der Bildt had made at least 550 telescopes, the majority of which were of a
139
The 1798 inventory of the Leiden observatory lists 75 instruments (Univ. Libr. Leiden, AC I- 260,
no. 29).
140
Nuyens, Camper’s travel journals (1939), 186; Martinus van Marum to Adriaan van Zeeberg, 11
August 1790, printed in E. Lefebvre and J. G. de Bruijn (editors), Martinus van Marum. Life and Work, 6
(1976), 381–5.
141
Turner (note 113), 287–98. For Rochon, see S. L. Chapin, ‘Light-Gathering Power in the French
Enlightenment: A Revolutionary Telescope Proposal’, in Actes XIIIe Congrès Int. Hist. Sc., 6 (1971,
published 1974), pp. 265–70.
142
Zuidervaart (note 27), 378–9. See also J. G. de Bruijn, ‘Astronomy’, in (note 140), 415–6.
Table 1.
No.
Name
Worked in
Worked from
Dresden
Amsterdam
Amsterdam
Amsterdam
Franeker
Leeuwarden
Groningen
Kleef
Franeker
Franeker; Amsterdam
The Hage
Franeker
Franeker
c.1711
[1717–1731]
c.1742
[v1736]
1745
[1750] 1753
[1731] v1755
Daniël Gabriel Fahrenheit
1686–1737
2
3
4
5
6
7
8
9
10
11
12
Jacobus van de Wall
Hendrik Prins
Jan Pietersz van der Bildt
Wytze Foppes Dongjuma
Gerrit Cramer
Louis Wurstemberguer
Johannes van der Bildt Jzn.
Henricus Aenaea
Wm de la Haye
Lubbertus van der Bildt Jzn.
Ids[zard] Gerbens van den Velde
Haarlem
Sibrand Taekes van de Vliet
Bauke Eisma van der Bildt
1700–1782
1696–1762
1709–1791
1707–1778
1707–1755
15
16
17
18
19
1738–c.1780
w1781
1740–1806
1753–1831
1754–1828
1742–1801
1745–1809
1770–1845
?–?
1791–1854
1791–1828
1795–1880
?–?
1794–1857
1821–1906
Franeker
Franeker
Buiksloot/Amsterdam
Franeker
Hijum
Hijum
Hijum
Dronrijp
Hallum
Buiksloot
St Anna Parochie
Hallum/Beetgum
Ternaard
Leiden
Menaldum
St Jacobi Parochi
Hallum
Herbajum
c.1762?
v1766
1764
v1767
1768–1779
1780v1786
v1774
1787–1806
1806–1831
v1786
v1786
v1786
1791
1798
1826–1845
1809
1824
v1828
v1829
[1829–1845]
1834
1832
Trained by
Autodidact
z
z
z
z
z
[1752]
z
Von Sprögel?
Fahrenheit?
Loré/Feyt?
Loré
z
z
Van der Bildt
Van der Bildt?
z
z
Van der Bildt
Van der Bildt
z
Foppes?
Foppes?
Foppes?
Van der Bildt
Van der Bildtand Foppes
Roelofs/Onderdewijngaart Canzius
z
z
z
z
Eisma Van der Bildt?
Roelofs
Roelofs
Roelofs
Rienks
Roelofs
445
20
21
22
23
24
25
26
27
28
Arjen Roelofs
Pieter Roelofs
Albert Roelofs
Rients Piers Salverda
Sieds Johannesz Rienks
Leiden
Jan Rooseboom
Roelof Hessels Hommema
Beert Johannes Gelder I
Worp van Peyma
Beijerinck
Rinse Beerts Gelder
T. F. Huisinga
Pieter Sierds Heidanus
Johannes Kiestra
1736–c.1780
1743–1810
Telescopes extant
The Reflecting Telescope in the Netherlands
Lived
1
13
14
Reflecting-telescope manufacturers from the Netherlands.
446
Huib J. Zuidervaart
Gregorian design.143 Inspired by this commercial success, the telescope production
was continued by a new generation. On the one hand, this was undertaken by
professional instrument-makers associated with the Franeker Academy, who used
Van der Bildt’s expertise in their work, and on the other hand, new ‘farmer
professors’ arose in the tradition of the self-taught natural philosopher and
instrument-maker, Wytze Foppes.
The first group included Sybrandt Taekes van de Vliet, for many years Van der
Bildt’s first assistant and, after 1791, his successor at the Franeker Academy. A
second disciple was Bauke Eisma van der Bildt, the grandson of the ‘master’.144
Probably also Ids Gerbens van de Velde belonged to Van der Bildt’s pupils. He was
employed at Franeker from 1768 onwards but moved in 1780 to Holland. Both Van
de Vliet and Van de Velde enjoyed the support of the Franeker professor Jan
Hendrik van Swinden, who had taken it upon himself ‘to help these two craftsmen,
my good friends, in advice and deeds’. Van Swinden personally guaranteed the
quality of their telescopes, especially those made by Van de Vliet who ‘for some
time has devoted himself to this’. 145
The second category of instrument-makers includes the brothers Arjen, Pieter,
and Albert Roelofs and their pupils, including Syds Johannes Rienks.146 That there
were two parallel schools of instrument-makers, who withheld essential technical
information from each other, is apparent from a contemporary statement saying
that Arjen Roelofs ‘never exactly knew the best way to polish the metal mirrors’.
Over and over, his mirrors were less shiny than those of Van der Bildt, in contrast
to the mirrors of Van der Bildt’s protégé’s Van de Vliet and Eisma van der Bildt.147
Clearly, the last were initiated in Van der Bildt’s experiences and techniques.
Moreover, Van der Bildt’s disappointing experience in the late 1760s had kept them
from working on larger telescopes.
7.4. The fiasco of Roelofs and Rienks
The farmers Arjen and Pieter Roelofs clearly had no such reservations. These
two brothers aimed ‘right from the start, to give telescopes a wider aperture than
143
The highest number known on a telescope by Jan van der Bildt is 536 (Louwman collection,
Wassenaar). In view of the conflict between Jan van der Bildt and his sons, it seems unlikely that their
production of telescopes is included in this number. The highest number known for Johannes van der
Bildt, Jr. is 63 (Museum Boerhaave, Leiden); Lubbertus van der Bildt is ranked at number 139 (Ottema
Kingma Foundation, now at the Eisinga planetarium, Franeker). The other telescope-makers in the
Netherlands did not use production numbers.
144
Both Sybrandt Taekes van de Vliet (1740–1806) and Bauke Eisma van der Bildt (1753–1831) were
educated by Jan van der Bildt the elder. In 1791, Van de Vliet succeeded his master as laboratory assistant at
the Franeker University. After his death in 1806, Van de Vliet was replaced by Eisma van der Bildt, who, after
1786, worked for a short time at Buiksloot in the neighbourhood of Amsterdam. After the closure of the
Franeker University in 1811, Van der Bildt’s grandson stayed in Franeker until his death in 1831.
145
J. H. van Swinden to J. Engelman, 10 November 1775 (University Library Leiden, BPL 755).
146
According to a statement made by A. G. Camper in 1817, the three brothers Roelofs were trained
by their grandfather, Pieter Roelofs, who was a ‘Lover of Mechanics and was very skilled in Physics’.
This Pieter Roelofs was a disciple of the telescope-builder, Foppes, from which he learned the ‘making of
eye-glasses’ and his other ‘skills in the art of seeing’. Of the three brothers, Arjen Roelofs (1754–1828)
was the most famous. See J. van der Bilt, De grote spiegelkijkers van Roelofs en Rienks (Leiden, 1951), 8;
Worp van Peyma, Levensberigten van Arjen Roelofs (Franeker, 1829), 82–85 and J. van der Bilt, ‘Arjen
Roelofs, sterrekundige (1754–1828)’, Hemel en Dampkring, wetensch. suppl. no. 3 (Auguest 1951), 41–63.
147
It was only around 1830 that Roelof Hessels Hommema, a telescope-builder trained by Roelofs,
learned how to make ‘better metal mirrors than his uncle [A. Roelofs] ever had known’. Van Peyma (note
146), 29; 145–6. See also A. Spoor, ‘Enige metingen en opmerkingen over spiegelkijkers van Rienks,
Hommema en Heidanus’, De Vrije Fries, 41 (1953), 108–11.
The Reflecting Telescope in the Netherlands
447
anyone up to that time had dared to do’.148 After having worked on their first
telescope for two years, they claimed to have achieved a better result than Short.149
At that time (about 1785), Herschel was not yet someone with whom they sought to
compare themselves. In light of the comment that the quality of Roelofs’ mirrors
was always lower than that of Van der Bildt’s, this claim was rather indefensible.
Nevertheless, full of self-confidence, the brothers gathered a group of faithful
followers (including Rienks, Hommema, Heidanus, and Van Peyma) with whom
the construction of reflecting telescopes was discussed and practised.150
These Frisian initiatives so impressed the Franeker professor Ekama that in
1809, he was of the opinion that the Frisians should be recognized for their special
talents in mathematics and mechanics.151 In his address about ‘the fortunate
aptitude of the Frisians for the mathematical sciences’, the telescope-builders were
also discussed. Ekama claimed that Rienks’ telescopes were so excellent that they
could scarcely be surpassed by telescopes of any other manufacturer. Ekema’s
opinion was based not on astronomical observations but on the distance from
which he could read a newspaper using one of Rienks’ telescopes.152 The earlyRomantic desire for ‘heroes’ from the Dutch soil turned out to be stronger than the
urge for a responsible scientific test, but it worked. Ekema’s rhetoric struck a
sympathetic note at the palace of the newly founded Kingdom of Holland. Louis
Napoleon, king since 1808, considered awarding Rienks a commission for the
construction of a large telescope with a mirror of ‘two-foot diameter’. A quick start
was made. The ‘director general of the arts and sciences’ of the Kingdom received
the order to carry out a feasibility study and to publish his findings. That happened
in 1810, and indeed, this official also trumpeted the qualities of the duo Roelofs and
Rienks.153 But again, the report was not based on even the slightest bit of
optical investigation. That eventually no ‘royal’ order did come to pass had a
simple reason: the sudden end, that autumn, of the Napoleonic ‘Kingdom of
Holland’.
In 1815, following the establishment of the Kingdom of the Netherlands, a new
opportunity arose. The old idea was dug up and submitted to the recently crowned
148
Van Peyma (note 146), 25–31.
This remark probably refers to the attempts of the Roelofs brothers to make their oculars
achromatic by combining several types of lenses. As Short died in 1768, he never succeeded in doing this.
The dating of their first telescope is based on an observation of the Mercury transit of 1786, given by Van
Peyma (note 146), 31.
150
Syds Johannes Rienks (1770–1845) from Ferweradeel developed his skills until he could make a
living as a professional instrument-maker. Trained by Roelofs, he worked for a short time in 1805 in the
instrument factory of Onderdewijngaart Canzius at Delft and later returned to Friesland. In 1826, he
moved to Leiden. See J. Van der Bilt, ‘Over de kleine kijkers en de microscopen van Sieds Johannes
Rienks’, Hemel en dampkring 50 (1952), 181–91. For the other telescope-builders, see G. A. Wumkes,
‘Worp van Peyma en zijn vrienden’, De Vrije Fries (1914), 150–77.
151
C. Ekama, Oratio de Frisia ingeniorum mathematicorum (Leovardie, 1809). Cornelis Ekama (1773–
1826) lectured Mathematics, Physics, and Navigation at Zierikzee from 1803 to 1807, when he became a
professor in Logics, Metaphysics and Astronomy at Franeker. In 1812, he moved to a professorship at
Leiden University. For Ekama and the disastrous affair of the large telescopes of Roelofs and Rienks, see
also Ph. H. Breuker, Friese cultuur in het jonge koninkrijk (Leiden, 2001), 9–10.
152
Van der Bilt (note 146), 6. The reading of the newspaper appeared to be possible at a distance of
420 feet (about 150 m). This test was conducted in the presence of the Franeker professors De Crane and
A. G. Camper.
153
J. Meerman, ‘Merkwaardige berigten wegens drie uitmuntende vervaardigers van optische en
andere physische instrumenten, thans in Vriesland levende, namelyk S. J. Rienks, Arjen Roelofs en
Banco [!] Eisma van der Bildt’, Algemeene Konst- en Letterbode (1810-II), 4–9; 19–25. Articles with the
same message were printed in different magazines. For this affair, see also Breuker (note 151), 9–10.
149
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Huib J. Zuidervaart
William I. In the mean time, Herschel’s fame had become the yardstick. It was
impressed upon the king that the combined talents of Roelofs and Rienks were
certainly in a position to ‘equal if not exceed the excellence of Herschel’s telescopes’.154 The production of the intended telescopes would just about guarantee
the discovery of a William’s Star, analogous to Herschel’s Georgian Star (the
name originally proposed for the newly discovered planet, Uranus). The new king
was quickly won over for the plan. In 1817, Rienks and Roelofs received the
commission to construct two large telescopes in a farmer’s shed at the Frisian
village of Berlicum. The instruments were destined for the observatories in Leyden
and Brussels. They needed to be of such a quality that they would ‘surpass the giant
telescope of the famous Herschel in England’.
It transpired that the project was doomed right from the start. The manufacture
of parabolic telescope mirrors with a diameter of 55 cm was far beyond the
capabilities of Roelofs, Rienks, and their assistant, Hommema. They did not have
the necessary experience, the necessary polishing techniques, or an optical method
to assess the results of the grinding and polishing while this was being carried out.
The announcement that they needed a ‘karnmolen’ (churn mill) for the construction
of their mirrors is most revealing.155 The project also lacked scientific supervision,
and so it was not until after the erection of the telescopes (in about 1828) that it
became clear that these telescopes, although of excellent exterior appearance, were
completely unsatisfactory for the intended astronomical observations. In 1850, the
unused Leiden telescope was sold as scrap. The second telescope, originally destined
for Brussels and later transported to the Utrecht Observatory, was also dismantled.
From this telescope, only a few minor parts of the finder and the ocular are still in
existence.156
7.5. The demise of telescope production in the Netherlands
Why did the reflecting telescope in the Netherlands have such a dramatically
different development compared with that in England? After all, not only could the
UK boast about the Herschel family, but up to the 1840s, the reflecting telescope
continued to enjoy moments of glory, for example with Lord Rosse, who, long
before the era of astro-photography, resolved the spiral structure of several
nebulae.157
The starting point in both countries seemed very similar. As early as 1752, Van
der Bildt’s products were found to be comparable with those from England. A
recent comparative study into the optical qualities of telescopes still in existence
confirms this opinion. According to the researcher, Willach, the ‘admirable quality’
of Van der Bildt’s mirrors is ‘equal to the quality of Short’s mirrors of comparable
size’.158 He considers Van der Bildt ‘by far the most serious competitor’ of Short.
Incidentally, Van der Bildt’s pupils also produced work of a high standard. In 1775,
the Franeker professor, Van Swinden, could boast that the reflecting telescopes
154
Van der Bilt (note 146), 11.
Ibidem, 179.
156
Utrecht University Museum, inv. nrs. 56.01–56.04. (Courtesy of Dr J. C. Deiman, emeritus curator
of the museum).
157
Allan Chapman, The Victorian Amateur Astronomer. Independent Astronomical Research in Britain
1820–1920 (Chichester, 1998).
158
R. Willach, ‘James Short and the development of the Reflecting Telescope’, Journal of the Antique
Telescope Society, 20 (2001), 3–18.
155
The Reflecting Telescope in the Netherlands
449
from Van de Vliet ‘were recently classed in Holland as better than the English’.159
How, then, could this demise of the telescope industry in the Netherlands
occur?
From a European perspective, it is an unmistakable fact that the level of Dutch
science at the start of the nineteenth century was not very impressive. Van Berkel
ascribed this low level first and foremost to the low number of university professors.
Most of them were too old, so there was insufficient new blood under their ranks.
Furthermore, these few professors had to teach too many subjects, which lowered
the level of their expertise.160 However this depressing situation within university
science perhaps may clarify the failure of scientific supervision in the project of
Roelofs and Rienks, it cannot explain the overall failure. After all, production of
scientific instruments is not the same as engaging in scientific activities. The history
of the development of the reflecting telescope illustrates this difference well. From
the very start, the development of the reflecting telescope was an undertaking that
took place outside the universities. Thanks to the work of Hadley and others, the
instrument could be produced in numbers by professional instrument-makers. In
the Netherlands, there was a similar development. Non-university enthusiasts such
as Van der Wall, Feyt, and Hemsterhuis contributed more to the development of
the telescope than any university lecturer. Therefore, other factors must be taken
into account to clarify the demise of the reflecting-telescope production in the
Netherlands. Both organizational and economic factors seem to offer the most
satisfactory explanation:
1. It appears that the Dutch telescope-builders were scarcely able to export their
instruments. Although Van der Bildt may have been Short’s equal technically
speaking, from a commercial viewpoint he was no match for Short and his
colleagues. Apart from a small market in Germany and in the Dutch colonies,
Van der Bildt did not manage to realize any sizeable export. This striking fact
equally applied to the majority of Dutch instrument-makers.161 Clearly, the
Dutch merchants were more concerned with the transfer of goods than with
the creation of an export market for products from their own soil.
2. However, in their home market, the Dutch instrument-makers did face
competition from abroad. After the establishment in Amsterdam of English
instrument-makers such as Benjamin Ayres, James Champneys, John Cuthbertson,
and John Traill, a direct link with the English market of scientific instruments
was assured.162 Soon there was scarcely any difference in price between telescopes made in the Netherlands and English ‘retail’. In 1773, Van der Bildt
159
J. H. van Swinden to J. Engelman, 10 November 1775 (Univ. Libr. Leiden, BPL 755).
Van Berkel (note 4), 109–10.
161
De Clercq (note 4), 329, and ‘The scientific instrument-making industry in the Netherlands in the
Nineteenth Century’, in P. R. de Clercq [ed.], Nineteenth-Century Scientific Instruments and Their
Makers, Amsterdam, 1985, 205–25, esp. 208, 210.
162
Benjamin Ayres was the brother-in-law of the London instrument-maker, Jonathan Sisson. James
Campneys had been an instrument-maker in London since about 1760. In 1766, he was convicted for
infringing Dollond’s patent on the achromatic telescope. See J. H. Leopold, ‘Some notes on Benjamin
Ayres’, in R. W. G. Anderson [et al.], Making Instruments Count. Essays on Historical Scientific
Instruments Presented to Gerard L’Estrange Turner, (Aldershot, 1993), 395–402; W. D. Hackmann, John
and Jonathan Cuthbertson. The Invention and Development of the Eighteenth Century Plate Electrical
Machine (Leyden, 1973). The Amsterdam retail in 1765 of John Traill, a former teacher at the Military
Academy at London, is mentioned by Van der Krogt (note 42), nos. 1223 and 1126.
160
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Huib J. Zuidervaart
charged between 200 and 250 guilders for a 2-foot telescope.163 According to
the price list published by John Cuthbertson that same year, he could deliver a
reflecting telescope for 220 guilders.164 In addition to this, there was a direct
import from abroad. When, during the years 1771–1774, Arnout Loten, a
former mayor of Utrecht, built an observatory on the roof of his house, he
obtained all of his instruments directly from English instrument-makers, such
as Adams, Bird, Nairne, and Dollond. No Dutch ‘konstenaar’ could get a foot
in the door at Loten.165 With the French era, the tide seemed to change for the
Dutch artisans. The supply from England was limited for a long time. Yet, an
instrument-making factory set up in 1797 by Onderdewijngaart Canzius in
Delft eventually failed to succeed. In 1810, after slightly more than 10 years of
production, this modern factory had to close its doors.166
3. Yet the most fatal factor of all was the economic recession that affected the
Netherlands during the last quarter of the eighteenth century. Furthermore,
the recession persisted for several decades. Owing to the collective impoverishment of Dutch society, there were gradually fewer amateurs who could
afford expensive scientific instruments. As early as 1768, a private observatory
in Middelburg that had been operational for decades was closed, not only
because the ‘accuracy of the instruments’ was no longer sufficient, but above
all because ‘a king’s income’ was needed to build ‘a good and well-provided
place of observation’.167 And in 1780, when the Frisian telescope-builder, Van
de Velde, moved from Franeker to Haarlem, it was doubted from the outset
that he would survive there. The number of local amateurs had greatly
diminished, and the largest local buyer, Teyler’s cabinet, had already ‘acquired
everything needed for a course in physics’. Van Marum, the manager of the
cabinet, informed Van de Velde that he did not need his services. If Van de
Velde had been there several years previously, the situation would have been
quite different. Then, as Van Marum put it, he would not ‘have had to travel
so much to Cuthbertson in Amsterdam and to Paauw in Leyden’.168
163
In 1773 Van der Bildt charged the following prices: 200 guilders for a 2-foot Gregorian telescope,
250 guilders for a 3-foot telescope and 350 guilders for a telescope with a mahogany stand (Jan van der
Bildt to Johannes Berghuis at Delft, 8 February and 22 March 1773; Teylers Museum, Haarlem, Family
archive Van Breda).
164
Catalogus van Mathematische, Philosophische en Optische Instrumenten, welke gemaakt en verkogt
worden bij John Cuthbertson [. .] te Amsterdam, bound after J. Cuthbertson, Algemeene Eigenschappen
van de Electriciteit (Amsterdam, 1773). A small reflecting telescope, signed CUTHBERTSON &
CHAMPNEY’S, AMSTERDAM, is in the collection of Museum Boerhaave, Leiden.
165
Zuidervaart (note 27), 329–33.
166
Peter de Clercq, ‘J.H. Onderdewijngaart Canzius, Instrument Manufacturer and Museum
Director’, Bulletin of the Scientific Instrument Society, 49 (1996), 22–4. A catalogue of 1804 mentions
‘Reflecting Telescopes’ of Gregorian, Cassegrain, Newtonian, and Herschelian design. It is not known
whether these telescopes were really made in Onderdewijngaarts factory. Not a single telescope seems to
have survived.
167
Laurens Duynewey de Munck to Dirk Klinkenberg, 10 August 1768, cited in H. J. Zuidervaart,
‘Astronomische waarnemingen en wetenschappelijke contacten van Jan de Munck (1687–1768),
stadsarchitect van Middelburg’, Archief. Mededelingen van het Koninklijk Zeeuwsch Genootschap der
wetenschappen (1987), 103–70.
168
J. Engelman to J. H. van Swinden, 5 October 1780 (Univ. Libr. Leiden, BPL 755). The Leiden
instrument-maker, Jan Paauw, was the successor, albeit not in an official capacity, to the former Van
Musschenbroek workshop.
The Reflecting Telescope in the Netherlands
451
8. Conclusions
If we survey the history of the reflecting telescope in the Netherlands, the
following facts are striking. The instrument made its entry in the Netherlands in
about 1730. Thanks to enthusiasts in Amsterdam, in whose elite environment
money, interest, but above all else leisure time and practical expertise were present,
the instrument obtained a firm footing in the Netherlands. Through Amsterdam,
the reflecting telescope was introduced in the Frisian University town of Franeker.
There the instrument received new chances due to the favourable coincidence of a
number of circumstances.
First, there was the personal inspiration of a man as Van der Bildt, who—given
the favourable market conditions in the 1740s—saw his chance and grabbed it with
both hands. The fact that Van der Bildt’s appointment as laboratory assistant at the
local university guaranteed a minimal income favoured this successful development,
as did the fact that the Franeker University was the only university in the
Netherlands to place a continuous emphasis on technically oriented practical
subjects. Finally, the presence of a kind of ‘royal court’ in Friesland appeared to be
of equal importance. Until the disappearance of this court in 1765, local scientific
instrument-makers were supported as a matter of court policy.
During the last quarter of the eighteenth century, the development stagnated.
This was due, on the one hand, to technical difficulties (in both Amsterdam and
Franeker, attempts to make a large reflecting telescope foundered) and, on the
other hand, to economic adversities. These adversities also affected the production
of the achromatic telescope. The instrument-making company, Van Deijl, seems, in
any case, to have stopped the manufacture of these telescopes in about 1790. A
chronic lack of raw materials also seems to have played a role.169 Furthermore,
with the death of Hemsterhuis in 1791, their biggest advocate for building
telescopes was gone.
Finally, the lack of personal cooperation between the instrument-makers
eventually became their downfall. Whereas, in England, the breakthrough of the
reflecting telescope could be attributed to the deliberate exchange of expertise,
this lack of exchange seemed in part to have contributed to the downfall of
the reflecting telescope in the Netherlands. And whereas, in Amsterdam, the
development and production of the achromatic refractor seem to have been the
beneficial consequence of exchanges in experience between men such as Bley, Van
Deijl, Feyt, and Hemsterhuis, it appears that Van der Bildt in Franeker shared little
of his expertise with others. Hemsterhuis had to get the young Van Aylva to spy to
find out the current state of play with Van der Bildt’s large telescope. His colleague,
Roelofs, possibly never knew about the problems with Van der Bildt’s large
telescope. Equally, Roelofs knew little about the finer aspects of Van der Bildt’s
mirror production. Experiences gained were apparently rarely passed on to others.
When a report was published in 1825, concerning the state of scientific instrumentmaking in the Netherlands, it was observed that the nation lacked a breeding
ground for people with sufficient training in theoretical mathematics and
mechanics.170
169
Turner (note 113), 294–96. However, Harmanus van Deijl (1738–1809) continued to work with
smaller lenses. Around 1806, he succeeded to make the first achromatic microscope objectives. See Van
Zuylen (note 109) and J. C. Deiman, ‘A Myth Revealed: the case of the ‘Beeldsnyder Achromatic
Objective’, Annals of Science, 48 (1991), 577–81.
170
De Clercq (note 161), 210.
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The Reflecting Telescope in the Netherlands
All of this, combined with the need, after the period of French rule, to
emphasize a Dutch national identity, led to an overestimation of the nation’s
ability. The romantic yearning for a ‘Fatherland Feeling’ took its toll.171 In the
early nineteenth century, royal support for the telescope project of Roelofs and
Rienks turned out to be more of a curse, than a blessing. A lack of openness fuelled
the fear of insulting the king by criticizing the telescopes ‘donated’ by him. The
scientific supervision was insufficient, and as a result, the project became a complete
failure.
The fiasco of Roelofs’ and Rienks’ reflecting telescopes manifested itself well
into the century. Although, round about 1850, the Netherlands had its share of
instrument-makers, foreign instruments were often favoured due to their price, high
quality, and immediate availability. Large optical instruments were no longer made
anywhere in the Netherlands. When, in 1853, criticism was expressed about the
procurement of foreign instruments by the ‘Royal Academy of Engineers’ at Delft,
a sarcastic question was posed in the defence as to whether ‘professor Kaiser, when
he set up his Leiden Observatory, would have done better, instead of ordering as he
did a telescope from Munich, to have ordered yet another Telescope à la
Rienks?’.172 Within the Netherlands, the reflecting telescope, once a statusacquiring icon of scientific pride, had become a symbol of technical inability and
stagnation.
171
For this period of Dutch Nationalism, see Het Vaderlandsch gevoel. Vergeten negentiende-eeuwse
schilderijen over onze geschiedenis (Amsterdam, 1978).
172
De Clercq (note 161), 216–7.