Download Evolution of the knowledge of electricity and

NOWOTWORY Journal of Oncology • 2007 • volume 57
Number 1 • 24e–33e
Historia medicinae
Evolution of the knowledge of electricity and electrotherapeutics
with special reference to X-rays & cancer
Part 2.
Alessandro Volta to James Clerk Maxwell
Richard F. Mould1, Jesse N. Aronowitz2
The first part of this article [1] recounting the history of electricity and of electrotherapeutics closed with the contribution
of Charles Coulomb (1736-1806), Luigi Galvani (1737-1798), Pierre Bertholon (1742-1800) and Jean-Paul Marat (17431793). This second installment continues chronologically with the story with Alessandro Volta (1745-1827) and ends with
Lord Kelvin (1824-1907) and James Clerk Maxwell (1831-1879). The concluding part (to be published in Nowotwory
2/2007), commences with Sir William Crookes (1832-1919) and closes with the electrotherapists of the early 20th century.
By then, X-ray therapy and radium brachytherapy had replaced electrotherapy as the alternative to surgery in the treatment
of cancer.
Key words: electrotherapeutics, electricity, X-rays, cancer
Alessandro Volta 1745-1827
Volta, professor of physics at the university of Pavia,
found that the quantity of electricity necessary to evoke
a convulsion in the legs of a freshly killed frog was
minute, some 50-60 times less than that which could
be detected by the most sensitive electrometer then
available [2]. This nerve-muscle preparation, called
by Volta the ‘animal electrometer’ was to be used to
measure minute currents for some 30 years. Several
years later he determined that the coupling of different
metals generated a current, which was the electromotive
force in Galvani’s frog leg preparation§. (Galvani had
believed that the tissues themselves had generated
‘animal electricity’)
Volta used this discovery in 1800 to construct the
first source of electricity. The ‘voltaic pile’: a column of
alternating discs of silver and zinc (or copper), separated
1
2
§
41 Ewhurst Avenue
South Croydon
Surrey CR2 0DH
United Kingdom
Department of Radiation Oncology
University of Massachusetts Medical School
Levine Cancer Center
33 Kendall Street
Worcester MA 01605
USA
The histories of Luigi Galvani and Alessandro Volta are intertwined. Part 1 in Nowotwory issue 2/2006 ended with Galvani
(1737-1778).
Figure 1. Volta’s pile. The dark layers in the piles in the centre
and bottom of the figure are pieces of brine soaked cardboard.
At the top of the figure is his ‘crown of cups’ (couronne de tasses),
consisting of a series of cups containing brine or dilute acid. The
cups are connected by compound strips, half zinc/half copper. The
difference in potential between the first and the last cups is proportional
to the number of pairs of metal strips. [3] (Courtesy The Wellcome
Trust, London).
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Figure 2. Volta demonstrating his pile to Napoleon in Paris, in 1801 (Courtesy The Science
Museum, South Kensington, London).
by cardboard saturated by a salt solution (Figure 1) which
produced a constant current of electricity [3]. Later
versions had the strips or discs of the dissimilar metals
immersed in brine or in a weak-acid electrolyte.
Figure 2 depicts Volta demonstrating his pile to
Napoleon who, perhaps understanding the significance of
the discovery, awarded him a gold medal and a pension.
Within a few years other investigators were constructing piles and carrying out experiments. In 1800
the chemist William Nicholson (1753-1815) and the
surgeon Anthony Carlisle (1768-1840) electrolytically
decomposed of water into hydrogen and oxygen [4].
William Cruickshank (1745-1800) fashioned a more
powerful pile of rectangular zinc and copper plates in
a resin insulated wooden trough [4-6]. Then in 1801,
William Hyde Wollaston (1766-1828) established the
identity of voltaic currents with frictional electricity, by
demonstrating that either can decompose water [7].
Humphry Davy 1778-1829
In 1806 Humphry Davy’s Royal Society Bakerian
Lecture of [8] contained the first clear exposition of the
mechanisms of electrolysis and of the voltaic battery [4].
Hans Christian Oersted 1777-1851
A relationship between magnetism and electricity
had long been suspected. Lightening had been known
to magnetise steel objects, but almost all attempts to
duplicate these effects with electricity had failed.
Then in 1820 a pharmacist in Copenhagen, Hans
Oersted, demonstrated that a magnetic needle will
orient itself at right angles to a nearby wire transmitting
an electric current. This linkage of galvanism (current
electricity) and magnetism provided a basis for the
detection of the current by its magnetic effect. The
instrument constructed on this principle was called
a ‘galvanometer’ (which rendered Galvani’s ‘animal
electrometer’ obsolete).
André Marie Ampère 1775-1836
In 1821 the French mathematician Ampère discovered
that current-bearing wires attract or repel each other. His
investigations led to an elaborate theory and a science
he labelled ‘electrodynamics’ to describe that part of
the science which is concerned with this force. It is now
known that these actions are purely magnetic and due to
stresses in the intervening medium [9]. Following are the
four laws of parallel and oblique circuits discovered by
Ampère which form the basis of his theory.
(1) Two parallel portions of a circuit attract one
another if the currents in them are flowing in the same
direction, and repel one another if the currents flow in
opposite directions.
(2) Two portions of circuits crossing one another
obliquely attract one another if both the currents run
either towards or from the point of crossing, and repel
one another if one runs to and the other from that
point.
(3) When an element of a circuit exerts a force on
another element of a circuit, that force always tends to
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urge the other in a direction at right angles to its own
direction.
(4) The force exerted between two parallel portions
of circuits is proportional to the product of the strengths
of the two currents, to the length of the portions, and
inversely proportional to the simple distance between
them.
Georg Simon Ohm 1787-1854
The mathematical formula stating the relationship
between current, electromotive force, and resistance
was the work of Georg Ohm. Ohm’s law states that the
current in a circuit (i) is directly proportional to the
electromotive force (E) and inversely proportional to the
resistance (R). That is, i = E/R (in the CGS system E is
measured in volts, R in ohms and i in amperes).
Ohm published his findings in 1827 but his ideas
were initially dismissed by his colleagues and he was
forced to resign his modest teaching position at the Jesuit
Gymnasium of Cologne. He lived in poverty for the next
six years until he was offered a post as the Director of
the Polytechnic School of Nüremberg. However, in 1841
the Royal Society in London recognized the significance
of his discovery and the following year admitted him as
a member. In 1854 he received his first professorship
at a Germany university, of experimental physics at the
University of Munich.
interviewed Faraday and discovered that he was selfeducated, by reading the books he was binding. Davy
offered him a temporary position, but by 1825 he had
become Superintendent of the laboratory. In 1864 he
was offered, but declined, the Presidency of the Royal
Institution.
In the 1830s, Michael Faraday studied the interaction
of electric and magnetic fields and demonstrated that
a moving magnetic field, or a fluctuating electric field,
could induce a current in a nearby circuit: the principle of
electromagnetic induction. These discoveries led to the
invention of the magneto-electric generator (or dynamo)
which uses a moving magnet to generate an alternating
current. It also led to the induction coil which induces
an alternating high voltage current from an interrupted
low voltage current. The use of alternating currents in
medicine became known as faradism, as distinct from
galvanism which used continuous (direct) current
generated by an electrochemical reaction.
Figure 3 illustrates a textbook technique [10] of
1873 for ‘general Faradisation’. Figure 4 is an ‘apparatus
for Faradization’ from a 1918 catalogue of electromedical and X-ray apparatus [11]. It depicts a device
Michael Faraday 1791-1867
Faraday, a bookbinder’s apprentice, had the temerity
to apply to Sir Humphry Davy in 1812 for a position
as scientific assistant at the Royal Institution. Davy
Figure 3. General faradisation in 1873 [9].
Figure 4. Apparatus for faradisation, advertised in a 1918 catalogue
mainly containing X-ray apparatus. It was described as ‘Dr Spamer’s
faradic battery’. A dry cell is included and an induction coil can be seen
at the back and a selection of electrodes at the front. In front of the
coil is an On/Off switch in front of which are three terminals, two of
which are seen to be labeled P and S, for primary and secondary current.
Batteries for galvanism were also sold by this company, with a choice of
20, 24, 28, 32 or 40 cells [11].
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Figure 5. The lettering on this 1824 oil painting by Edmund Bristow states ‘Medical
electricity for the poor gratis from 8 till 10 in the morning. Cupping.‘ (Courtesy The
Wellcome Trust, London).
that combines galvanic and faradic electricity. That is,
batteries with an induction coil in order to step up the
voltage. This overcame the shortcomings of batteries
(low voltage) and dynamos (low current).
For comparison with Figure 3, Figure 5 is from the
1820s and shows a more graphic depiction of galvanism
being given by an electrotherapist to his patient
Electromagnetic induction led to the construction
of the induction coil and transformer that produced the
strong electrical currents of high voltage used by Röntgen
and others when operating X-ray tubes. Figures 6-8 [12,
13].
Figure 6. This journalistic illustration in the April 1896 issue of The
Windsor Magazine is a good likeness of Röntgen but there is an obvious
error: the discharge tube is cylindrical, rather than the historically
correct pear-shape [12].
Figure 7. X-ray tube electrical circuit (the batteries are not shown)
in a German pamphlet of 1896. J = Insulator. R = X-ray tube. K =
Photographic plate. O = Object to be X-ray photographed [13].
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system was used by Samuel Morse (1791-1872) who is
credited with the invention of the telegraph although he
knew of the earlier work of Henry..
Guillaume Duchenne 1806-1875
Figure 8. Induction coils advertised in 1901 in the Journal of the Röntgen
Society. Many commercial companies sold these coils which were often
referred to as Ruhmkorff coils after Heinrich Ruhmkorff (1803-1877).
After working in Germany as an apprentice mechanic and in England
with Joseph Brahmah (1748-1814), the inventor of the hydraulic press,
he opened a shop in Paris in 1855 for the production of electrical
apparatus. In 1858 he was awarded a 50,000 franc prize by Emperor
Napoleon III for the most important discovery in the application of
electricity, for a coil he built in 1851.
Joseph Henry 1797-1878
Henry, the first Secretary of the Smithsonian Institution,
was the leading American scientist after Benjamin
Franklin. His chief scientific contributions were in
the field of electromagnetism. He discovered the
phenomenon of self-inductance. Oersted and others
had observed magnetic effects from electric currents,
but Henry was the first to wind insulated wires around
an iron core in order to generate electromagnetism.
Today, Faraday is recognized as the discoverer of mutual
inductance (the basis of transformers) whereas Henry is
credited with the discovery of self-inductance.
Henry’s electromagnet made for Yale could lift
2,300 pounds and a later one constructed for Princeton
could lift 3,500 pounds. It was at Nassau Hall, Princeton,
that rigged two long wires one in front of and one behind
the he building; demonstrating that he was able to send
a signal by induction through the building. This was the
earliest demonstration of wireless telegraphy. Also, whilst
at Princeton, (for sending signals between his laboratory
and his home) he used a system with a remote electromagnet to close a switch for a stronger local circuit. This
was in effect an invention of the magnetic relay. A similar
Duchenne was a pioneering neurophysiologist and
one of the earliest physicians to employ faradism. His
career began as a general practitioner in his home town
of Boulogne but his fascination with electrotherapy
led to self-education in electronics (he devised his own
equipment), and his eventual relocation to Paris, to
obtain a wider array of clinical material. Rather than seek
a lucrative hospital appointment, he roamed the wards of
Paris’s public hospitals, seeking neurological cases for his
studies. At first considered something of an eccentric, his
Paris colleagues eventually recognised him as a leading
neuropathologist. Among his colleagues was the French
neuropathologist Jean-Martin Charcot (1825-1893).
Duchenne devised a technique, localised faradisation, consisting of nerve stimulation through moist
electrodes, avoiding distress to the overlying skin. He
dismissed franklinism, because the static charges largely
remained on the skin surface and required painful sparks
to stimulate the underlying nerves and muscles. He
decried galvanism because the currents dessicated and
cauterised the skin.
An interesting application of faradism was its use
to impede muscular wasting in degenerative diseases
by means of electrical stimulation. He is recognised as
the first who gave the definitive description with the
clinical, electrical and pathological features of the disease
now termed the Duchenne type of muscular dystrophy
[15].
Duchenne photographed the stimulation of the
facial expressions of emotions by electrical stimulation,
demonstrating that the facial muscles of expression
were grouped by individual nerves. The theory that the
nervous system had evolved so that emotions could be
expressed by a single nerve had been previously proposed
by Charles Darwin (1809-1882).
Duchenne’s 1856 experiments were performed upon
mental patients in the Hôpital Salpêtrière. His principal
subject ‘the old man’, was an ideal subject because he
was afflicted with almost total amnesia, and allowed
uncomfortable experiments to be repeated (Figure 9).
This work was published in 1862 as The Mechanisms of
Human Facial Expression [14, 15].
Carlo Matteucci 1811-1868
and Emil du Bois-Reymond 1818-1896
A professor of physics at Pisa, Carlo Matteucci, extending
the work of Galvani, showed that an electric current
accompanies each heart beat. He used a preparation
known as a ‘rheoscopic frog’ in which the cut nerve of
a frog’s leg was used as the electrical sensor and the
twitching of the muscle as the visual sign of electrical
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Figure 9a.
Figure 9b
.
Figure 9. Duchenne with his electrodes applied to the face of ‘the old man’ (a). Example of eight facial expressions (b).
(a Courtesy The Science Museum, South Kensington, London; b Courtesy The Wellcome Library, London).
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Figure 10. First demonstration of cineradiography, 1896 [17].
activity [16]. In 1846 he invented they kymograph, used
by physiologists for recording blood pressure.
This would not be the last time that a frog’s leg
woud be used as a test object. In 1896 John Macintyre
(1857-1928), medical electrician at Glasgow Royal
Informary, used a frog’s leg to demonstrate cineradiography (Figure 10) [17].
The German physician and physiologist Emil du
Bois-Reymond (1818-1896) extended the experiments
of Matteucci, demonstrating that muscles and nerves
generate electrical currents. These physiological
revelations provided a rationale for electrotherapeutics.
Golding Bird 1814-1854
Golding Bird’s work on electrotherapeutics was
influential during the 1830s, in part because he was both
a physician and an electrician. His clinical work with
galvanism, faradism, and static electricity was undertaken
in the ‘Electricity Room’ at Guy’s Hospital, London.
His subjects came from London’s lower working class
population.
A series of influential lectures on electrophysiology
that Bird delivered to the Royal College of Physicians in
1847 drew a connection between biology and electricity,
replacing the empirical use of electrotherapy with
a rational one [18]. He kept detailed case histories on his
patients: one such history was of a 15-year old girl with
hysterical paralysis of the left side of her body following
an ankle injury. Her neurological deficit was reversed
by a two week series of daily electrical shocks from her
sacrum to her toes.
Robert Remak 1815-1865
Remak began his medical career as a neuroanatomnist;
several neurological structures that he discovered are
named after him. He had advanced the notion that
cellular proliferation was due to division of pre-existing
cells, and described (and named) the embryo’s three
germ layers: he may well be considered the father of
embryology. But academic advancement at the University
of Berlin was denied because he would not renounce his
Jewish faith. Embittered, he resigned his appointment
and developed a second career, in electrotherapeutics.
His neuroanatomy background was invaluable as
a proponent of electrotherapy. He became dean of the
German galvanists, which included Wilhelm Erb (18401921), a pioneer electrodiagnostician.
Heinrich Geissler 1815-1879
and Johann Hittorf 1824-1914
Johann Heinrich Geissler was a German glassblower
after whom the Geissler mercury pump, designed 1855,
and Geissler tube are named. In 1854 he opened a shop
in Bonn to make scientific apparatus. He produced
glass tubes of many different complex shapes. Using
his new pump, enough air could be extracted from his
glass tubes to produce a relatively high vacuum, thereby
improving upon available discharge tubes. An additional
improvement was the use of platinum wire terminals,
as the metal’s expansion when heated matched that of
glass.
Geissler produced luminous colour effects by
applying high voltage currents from a Ruhmkorff coil
(Figure 8) and admitting small quantities of various
gases into his tubes. Two quotes from 1897 show the
influence Geissler made on scientists. At the end of
the 19th century it was stated ‘The beautiful glow of the
Geissler tubes lent a fresh attraction to the study (of
electrical discharges)’; and ‘Geissler tubes elicit glows of
many colours, vieing in beauty with the fleeting tints of
the aurora polaris’ [19].
One of the earliest types of quality control
measurement with X-ray tubes consisted of simply
looking at the colour of the glass bulb when X-rays were
produced. Figure 11 is of a self-regulating X-ray tube
manufactured by Queen & Company of Philadelphia
before 1904 [20, 21]. The dark green colour (Figure
11a) was produced when the tube was operating at a low
vacuum: a lighter green colour was observed when the
tube was operating properly.
The red colour (Figure 11b) was seen shortly after
the tube had been punctured. The fluorescence depended
on the type of glass of which the bulb was constructed.
Glass in early tubes usually contained silicates of
potassium, sodium and calcium; but sometimes also lead,
manganese, aluminium and boron.
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Figure 11a
Figure 11 b
Figure 11. Quality assurance by viewing the fluorescence of the glass of an X-ray tube. (a) A low vacuum
produced the dark green colour. (b)When a tube was punctured the colour changed to red. These colour
photographs appeared in textbooks of 1904 and 1907 [19, 20].
Most X-ray tubes of German origin fluoresced in
yellow-green as they were normally made of potassium
glass. Tubes manufactured in the United Kingdom were
usually made of lead glass and fluoresced in blue [22].
Julius Plücker (1801-1868) was a mathematician
and physicist who studied in both Germany and France.
Using Geissler tubes he observed glass fluorescence in
discharge tubes opposite one of the electrodes. He also
observed cathode rays using a Geissler tube in 1859.
Johan Wilhelm Hittorf (1824-1914), a student of
Julius Plücker, made discharge tubes with a much higher
vacuum, that either Plücker or Geissler. Using an Lshaped tube [23] he noted that the electrical discharge
always occurred in the arm with the negative electrode.
It was not until a few years later than Eugen
Goldstein (1850-1930) used the term ‘cathode rays’
to describe the visible stream between the electrodes
of excited vacuum tubes. Up to the early 1930s, X-ray
physics books often introduced the subject with an
explanation of a simple discharge tube and mention of
Geissler (Figure 12) [24, 25].
Schall in 1932 describes the phenomena as follows
[25]. ‘When the air in the tube is removed till the pressure
inside falls to about 1/100th part of an atmosphere, so that
the mercury column of a barometer would have dropped
from 760 mm to 8 mm, the sharp-edged crackling sparks
(Figure 12a) change to a furry noiseless caterpillar-like
band (Figure 12b).
At a pressure of 1 mm mercury the diameter of the
discharge has increased, till the whole tube is filled with
light. The resistance to the passage of electricity is much
less, and a spark, which in air, would only just bridge
a gap of 5 cm can discharge through a tube 100 cm long
when the air pressure is thus reduced. This phenomenon
was used by Geissler. When the pressure is still further
reduced a dark patch, known as the Faraday dark space,
surrounds the cathode (Figure 12c).
At a yet lower pressure the luminosity of the tube
breaks up into a number of bands known as striations,
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whilst a second dark space appears round the cathode,
known as the Crookes’ dark space (Figure 12d). When
the pressure has fallen to 0.001 mm or thereabouts the
dark space round the cathode fills the whole tube to the
exclusion of all luminosity, but now the glass walls light
up brightly with fluorescence.
Hittorf in 1869 discovered that the dark space
within the tube under these conditions is not merely
an emptiness, but that there is evidence of rays which
appear to come from the cathode and are therefore
called cathode rays’.
A much earlier illustration showing discharge
patterns through an evacuated tube is seen in Figure 13,
taken from the 18th century book by Abbé Nollet [26].
a
b
Lord Kelvin (William Thomson) 1824-1907
c
d
Figure 12. Discharge tube phenomena, after Schall [24].
1, 2, 4, 7 – to air pump
3, 6 – Faraday dark space
5 – Crookes’ dark space
Figure 13. Abbé Nollet’s discharge patterns through an evacuated
tube [26].
William Thomson (elevated to Lord Kelvin in 1892)
was a mathematical physicist and engineer who, in 1846
(at the age of 22) was appointed professor of natural
philosophy at the University of Glasgow. In 1845 he
gave the first mathematical development of Faraday’s
idea that electric induction takes place through an
intervening medium or ‘dialectric’ and not by some
‘action at a distance’. He also designed the quadrant
electrometer to provide more accurate measurements
of electric current and in 1851 gave a general theory of
thermoelectric properties
James Clerk Maxwell 1831-1879
The Scottish mathematician Maxwell, was a professor
first in Aberdeen 1856-60, then at King’s College,
London in 1860 and later in 1871, was appointed the
first Cavendish professor of physics at Cambridge. He
interpreted the earlier work of Faraday, Ampère and
others, in terms of advanced mathematics forming a set
of equations expressing the basic laws of electricity and
magnetism. They are collectively known as Maxwell’s
equations; they were first presented to the Royal Society
in 1864. They describe the behaviour of both electric and
magnetic fields, as well as their interaction with matter.
Maxwell’s electromagnetic theory of light stated that
light waves are not mere mechanical motions of the ether
but are oscillations which are partly electrical and partly
magnetic. The oscillating electrical displacements are
accompanied by oscillating magnetic fields at right angles.
In 1865 he wrote that ‘their velocity is so nearly that of
light, that it seems we have strong reason to conclude that
light itself (including radiant heat, and other radiations
if any) is an electromagnetic disturbance in the form
of waves propagated through the electromagnetic field
according to electromagnetic laws’ [27].
Maxwell then believed that the propagation of light
required a medium for the waves, called the ‘ether’.
Over time, the idea of the existence of such a medium
in all space, yet undetectable by mechanical means, was
abandoned. It was the work of Albert Michelson (18531951) that proved the non-existence of the ether. His
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work culminated in the first Nobel Prize awarded to an
American, for physics, in 1907.
Hermann von Helmholtz 1821-1894
and Heinrich Hertz 1857-1894
12.
13.
14.
In 1870 Hermann von Helmholtz derived the correct laws
of reflection and refraction from Maxwell’s equations
and, in 1881, posited the concept that charged particles
within atoms would be consistent with Maxwell’s and
Faraday’s ideas. He allowed for X-rays and radio waves in
his theoretical dispersion theory of light, specifying their
properties which included the power to pass through
opaque material. He might therefore be considered to
be the ‘theoretical discoverer’ of X-rays as distinct from
Röntgen who was the experimental discoverer [28]. Von
Helmholz’ first important scientific achievement was
in 1847 in his physics treatise on the conservation of
energy.
Heinrich Rudolf Hertz, one of von Helmholz’
students, was the first to experimentally demonstrate
electromagnetic radiation, showing that electric signals
can travel through open air (as predicted by Maxwell
and Faraday). This is the basis for the invention of the
wireless. Hertz also worked on electric discharge tubes
and observed that cathode rays could pass through a thin
sheet of aluminium placed within the tube. In addition,
he discovered the photoelectric effect when he observed
that a charged object loses its charge more readily when
illuminated by ultraviolet light.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
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Ward HS. Marvels of the new light. Notes on the Röntgen rays. Windsor
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Dittmar A. Prof. Röntgen’s “X” rays and their applications in the new
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Munro J. The story of electricity. London: George Newnes, 1897; and
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Kassabian MK. Electro-therapeutics and Röntgen rays. Philadelphia:
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Pusey WA, Caldwell EW. The practical application of Röntgen rays in
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Paper received: 18 April 2006
Accepted: 9 July 2006
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p 394.
11. Watson & Sons (Electro-Medical) Ltd. Price list [No. 228] of apparatus
for radiography, high frequency, electrolysis, light, hydro-therapy, radioscopy,