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Sir Charles Wheatstone FRS (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three - dimensional images), and the Playfair cipher (an encryption technique). However, Wheatstone is best known for his contributions in the development of the Wheatstone bridge, originally invented by Samuel Hunter Christie, which is used to measure an unknown electrical resistance, and as a major figure in the development of telegraphy. Charles Wheatstone was born near Gloucester. His father was a music seller in the town, who moved to 128 Pall Mall, London, four years later, becoming a teacher of the flute. Charles, the second son, went to a village school, near Gloucester, and afterwards to several institutions in London. One of them was in Kennington, and kept by a Mrs. Castlemaine, who was astonished at his rapid progress. From another he ran away, but was captured at Windsor, not far from the theatre of his practical telegraph. As a boy he was very shy and sensitive, liking well to retire into an attic, without any other company than his own thoughts. When he was about fourteen years old he was apprenticed to his uncle and namesake, a maker and seller of musical instruments (such as the Wheatstone concertina), at 436 Strand, London; but he showed little taste for handicraft or business, and loved better to study books. His father encouraged him in this, and finally took him out of the uncle's charge. At the age of fifteen, Wheatstone translated French poetry, and wrote two songs, one of which was given to his uncle, who published it without knowing it as his nephew's composition. Some lines of his on the lyre became the motto of an engraving by Bartolozzi. Small for his age, but with a fine brow, and intelligent blue eyes, he often visited an old book stall in the vicinity of Pall Mall, which was then a dilapidated and unpaved thoroughfare. Most of his pocket money was spent in purchasing the books which had taken his fancy, whether fairy tales, history, or science. One day, to the surprise of the bookseller, he coveted a volume on the discoveries of Volta in electricity, but not having the price, he saved his pennies and secured the volume. It was written in French, and so he was obliged to save again, until he could buy a dictionary. Then he began to read the volume, and, with the help of his elder brother, William, to repeat the experiments described in it, with a home made battery, in the scullery behind his father's house. In constructing the battery, the boy philosophers ran short of money to procure the requisite copper plates. They had only a few copper coins left. A happy thought occurred to Charles, who was the leading spirit in these researches, 'We must use the pennies themselves,' said he, and the battery was soon complete. At Christchurch, Marylebone, on 12 February 1847, Wheatstone was married. His wife was the daughter of a Taunton tradesman, and of handsome appearance. She died in 1866, leaving a family of five young children to his care. His domestic life was quiet and uneventful. Though
silent and reserved in public, Wheatstone was a clear and voluble
talker in private, if taken on his favourite studies, and his small but
active person, his plain but intelligent countenance, was full of
animation. Sir Henry Taylor tells us that he once observed Wheatstone
at an evening party in Oxford earnestly holding forth to Lord
Palmerston on the capabilities of his telegraph. 'You don't say so!'
exclaimed the statesman. 'I must get you to tell that to the Lord
Chancellor.' And so saying, he fastened the electrician on Lord
Westbury, and effected his escape. A reminiscence of this interview may
have prompted Palmerston to remark that a time was coming when a
minister might be asked in Parliament if war had broken out in India,
and would reply, 'Wait a minute; I'll just telegraph to the
Governor - General, and let you know.' Wheatstone was knighted in 1868, after his completion of the automatic telegraph. He had previously been made a Chevalier of the Legion of Honour.
Some thirty-four distinctions and diplomas of home or foreign societies
bore witness to his scientific reputation. Since 1836 he had been a
Fellow of the Royal Society, and in 1859 he was elected a foreign
member of the Royal Swedish Academy of Sciences, and in 1873 a Foreign Associate of the French Academy of Sciences.
The same year he was awarded the Ampere Medal by the French Society for
the Encouragement of National Industry. In 1875 he was created an
honorary member of the Institution of Civil Engineers. He was a D.C.L.
of Oxford and an LL.D. of Cambridge. While
on a visit to Paris during the autumn of 1875, and engaged in
perfecting his receiving instrument for submarine cables, he caught a
cold, which produced inflammation of the lungs, an illness from which
he died in Paris, on 19 October 1875. A memorial service was held in
the Anglican Chapel, Paris, and attended by a deputation of the
Academy. His remains were taken to his home in Park Crescent, London,
(marked by a blue plaque today) and buried in Kensal Green Cemetery. In
September 1821, Wheatstone brought himself into public notice by
exhibiting the 'Enchanted Lyre,' or 'Aconcryptophone,' at a music shop
at Pall Mall and in the Adelaide Gallery. It consisted of a mimic lyre
hung from the ceiling by a cord, and emitting the strains of several
instruments — the piano, harp, and dulcimer.
In reality it was a mere sounding box, and the cord was a steel rod
that conveyed the vibrations of the music from the several instruments
which were played out of sight and earshot. At this period Wheatstone
made numerous experiments on sound and its transmission. Some of his
results are preserved in Thomson's Annals of Philosophy for
1823. He recognised that sound is propagated by waves or oscillations
of the atmosphere, as light was then believed to be by undulations of
the luminiferous ether.
Water, and solid bodies, such as glass, or metal, or sonorous wood,
convey the modulations with high velocity, and he conceived the plan of
transmitting sound signals, music, or speech to long distances by this
means. He estimated that sound would travel 200 miles per second (322 km/s) through solid rods, and proposed to telegraph from London to Edinburgh in this way. He even called his arrangement a 'telephone.' (Robert Hooke, in his Micrographia,
published in 1667, writes: 'I can assure the reader that I have, by the
help of a distended wire, propagated the sound to a very considerable
distance in an instant, or with as seemingly quick a motion as that of
light.' Nor was it essential the wire should be straight; it might be
bent into angles. This property is the basis of the mechanical or
lover's telephone, said to have been known to the Chinese many
centuries ago. Hooke also considered the possibility of finding a way
to quicken our powers of hearing.) A writer in the Repository of Arts for
1 September 1821, in referring to the 'Enchanted Lyre,' beholds the
prospect of an opera being performed at the King's Theatre, and enjoyed at the Hanover Square Rooms, or even at the Horns Tavern, Kennington. The vibrations are to travel through underground conductors, like to gas in pipes. Besides
transmitting sounds to a distance, Wheatstone devised a simple
instrument for augmenting feeble sounds, to which he gave the name of
'Microphone.' It consisted of two slender rods, which conveyed the
mechanical vibrations to both ears, and is quite different from the electrical microphone of Professor Hughes. In
1823, his uncle, the musical instrument maker, died, and Wheatstone,
with his elder brother, William, took over the business. Charles had no
great liking for the commercial part, but his ingenuity found a vent in
making improvements on the existing instruments, and in devising
philosophical toys. At the end of six years he retired from the
undertaking. In 1827, Wheatstone introduced his 'kaleidophone',
a device for rendering the vibrations of a sounding body apparent to
the eye. It consists of a metal rod, carrying at its end a silvered
bead, which reflects a 'spot' of light. As the rod vibrates the spot is
seen to describe complicated figures in the air, like a spark whirled
about in the darkness. His photometer was
probably suggested by this appliance. It enables two lights to be
compared by the relative brightness of their reflections in a silvered
bead, which describes a narrow ellipse, so as to draw the spots into
parallel lines. In 1828, Wheatstone improved the German wind instrument, called the Mundharmonika, until it became the popular concertina, patented on 19 December 1829. The portable harmonium is another of his inventions, which gained a prize medal at the Great Exhibition of 1851. He also improved the speaking machine of De Kempelen, and endorsed the opinion of Sir David Brewster, that before the end of this century a singing and talking apparatus would be among the conquests of science. In 1834, Wheatstone, who had won a name for himself, was appointed to the Chair of Experimental Physics in King's College London.
But his first course of lectures on Sound were a complete failure,
owing to an invincible repugnance to public speaking, and a distrust of
his powers in that direction. In the rostrum he was tongue tied and
incapable, sometimes turning his back on the audience and mumbling to
the diagrams on the wall. In the laboratory he felt himself at home,
and ever after confined his duties mostly to demonstration. He
achieved renown by a great experiment — the measurement of the velocity
of electricity in a wire. He cut the wire at the middle, to form a gap
which a spark might leap across, and connected its ends to the poles of
a Leyden jar filled
with electricity. Three sparks were thus produced, one at either end of
the wire, and another at the middle. He mounted a tiny mirror on the
works of a watch, so that it revolved at a high velocity, and observed
the reflections of his three sparks in it. The points of the wire were
so arranged that if the sparks were instantaneous, their reflections
would appear in one straight line; but the middle one was seen to lag
behind the others, because it was an instant later. The electricity had
taken a certain time to travel from the ends of the wire to the middle.
This time was found by measuring the amount of lag, and comparing it
with the known velocity of the mirror. Having got the time, he had only
to compare that with the length of half the wire, and he could find the
velocity of electricity. His results gave a calculated velocity of
288,000 miles per second, i.e. faster than what we now know to be the
speed of light, but were nonetheless an interesting approximation. It
was afterwards found that the velocity of an electric field travelling
in a cable depends on the nature of the conductor, its resistance, and its electrostatic capacity. Michael Faraday showed,
for example, that its velocity in a submarine wire, coated with
insulator and surrounded with water, is only 144,000 miles per second
(232,000 km/s), or still less. Wheatstone's device of the
revolving mirror was afterwards employed by Léon Foucault and Hippolyte Fizeau to measure the velocity of light. Wheatstone and others also contributed to early spectroscopy through the discovery and exploitation of spectral emission lines. As
John Munro wrote in 1891, "In 1835, at the Dublin meeting of the
British Association, Wheatstone showed that when metals were
volatilised in the electric spark, their light, examined through a
prism, revealed certain rays which were characteristic of them. Thus
the kind of metals which formed the sparking points could be determined
by analysing the light of the spark. This suggestion has been of great service in spectrum analysis, and as applied by Robert Bunsen, Gustav Robert Kirchhoff, and others, has led to the discovery of several new elements, such as rubidium and thallium, as well as increasing our knowledge of the heavenly bodies."
Wheatstone
abandoned his idea of transmitting intelligence by the mechanical
vibration of rods, and took up the electric telegraph. In 1835 he
lectured on the system of
Baron Schilling,
and declared that the means were already known by which an electric
telegraph could be made of great service to the world. He made
experiments with a plan of his own, and not only proposed to lay an
experimental line across the Thames, but to establish it on the London
and Birmingham Railway. Before these plans were carried out, however, he received a visit from Mr William Fothergill Cooke at his house in Conduit Street on 27 February 1837, which had an important influence on his future. Mr. Cooke was an officer in the Madras army, who, being home on furlough, was attending some lectures on anatomy at the University of Heidelberg, where, on 6 March 1836, he witnessed a demonstration with the telegraph of Professor Moncke,
and was so impressed with its importance, that he forsook his medical
studies and devoted all his efforts to the work of introducing the
telegraph. He returned to London soon after, and was able to exhibit a
telegraph with three needles in January, 1837. Feeling his want of
scientific knowledge, he consulted Faraday and Dr. Roget, the latter of
whom sent him to Wheatstone. At
a second interview, Mr. Cooke told Wheatstone of his intention to bring
out a working telegraph, and explained his method. Wheatstone,
according to his own statement, remarked to Cooke that the method would
not act, and produced his own experimental telegraph. Finally, Cooke
proposed that they should enter into a partnership, but Wheatstone was
at first reluctant to comply. He was a well known man of science, and
had meant to publish his results without seeking to make capital of
them. Cooke, on the other hand, declared that his sole object was to
make a fortune from the scheme. In May they agreed to join their
forces, Wheatstone contributing the scientific, and Cooke the
administrative talent. The deed of partnership was dated 19 November
1837. A joint patent was taken out for their inventions, including the
five - needle telegraph of Wheatstone, and
an alarm worked by a relay, in which the current, by dipping a needle
into mercury, completed a local circuit, and released the detent of a
clockwork. The
five - needle telegraph, which was mainly, if not entirely, due to
Wheatstone, was similar to that of Schilling, and based on the
principle enunciated by André - Marie Ampère —
that is to say, the current was sent into the line by completing the
circuit of the battery with a make and break key, and at the other end
it passed through a coil of wire surrounding a magnetic needle free to
turn round its centre. According as one pole of the battery or the
other was applied to the line by means of the key, the current
deflected the needle to one side or the other. There were five separate
circuits actuating five different needles. The latter were pivoted in
rows across the middle of a dial shaped like a diamond, and having the
letters of the alphabet arranged upon it in such a way that a letter
was literally pointed out by the current deflecting two of the needles
towards it.
An experimental line, with a sixth return wire, was run between the Euston terminus and Camden Town station
of the London and North Western Railway on 25 July 1837. The actual
distance was only one and a half mile (2.4 km), but spare wire had
been inserted in the circuit to increase its length. It was late in the
evening before the trial took place. Mr Cooke was in charge at Camden
Town, while Mr Robert Stephenson and
other gentlemen looked on; and Wheatstone sat at his instrument in a
dingy little room, lit by a tallow candle, near the booking office at
Euston. Wheatstone sent the first message, to which Cooke replied, and
'never' said Wheatstone, 'did I feel such a tumultuous sensation
before, as when, all alone in the still room, I heard the needles
click, and as I spelled the words, I felt all the magnitude of the
invention pronounced to be practicable beyond cavil or dispute.' In
spite of this trial, however, the directors of the railway treated the
'new - fangled' invention with indifference, and requested its removal. In July 1839, however, it was favoured by the Great Western Railway, and a line erected from the Paddington station terminus to West Drayton railway station,
a distance of thirteen miles (21 km). Part of the wire was laid
underground at first, but subsequently all of it was raised on posts
along the line. Their circuit was eventually extended to Slough in
1841, and was publicly exhibited at Paddington as a marvel of science,
which could transmit fifty signals a distance of 280,000 miles per
minute (7,500 km/s). The price of admission was a shilling
(£0.05), and in 1844 one fascinated observer recorded the
following: "It is perfect from the terminus of the Great Western as far as Slough – that is, eighteen miles; the wires being in some places underground in tubes, and in others high up in the air, which last, he says, is by far the best plan. We asked if the weather did not affect the wires, but he said not; a violent thunderstorm might ring a bell, but no more. We were taken into a small room (we being Mrs Drummond, Miss Philips, Harry Codrington and myself – and afterwards the Milmans and Mr Rich) where were several wooden cases containing different sorts of telegraphs. In one sort every word was spelt, and as each letter was placed in turn in a particular position, the machinery caused the electric fluid to run down the line, where it made the letter show itself at Slough, by what machinery he could not undertake to explain. After each word came a sign from Slough, signifying "I understand", coming certainly in less than one second from the end of the word..... Another prints the messages it brings, so that if no-one attended to the bell, ....the message would not be lost. This is effected by the electrical fluid causing a little hammer to strike the letter which presents itself, the letter which is raised hits some manifold writing paper (a new invention, black paper which, if pressed, leaves an indelible black mark), by which means the impression is left on white paper beneath. This was the most ingenious of all, and apparently Mr. Wheatstone's favourite; he was very good - natured in explaining but understands it so well himself that he cannot feel how little we know about it, and goes too fast for such ignorant folk to follow him in everything. Mrs Drummond told me he is wonderful for the rapidity with which he thinks and his power of invention; he invents so many things that he cannot put half his ideas into execution, but leaves them to be picked up and used by others, who get the credit of them."
The public took to the new invention after the capture of the murderer
John Tawell,
who in 1845, had become the first person to be arrested as the result
of telecommunications technology. In the same year, Wheatstone
introduced two improved forms of the apparatus, namely, the 'single'
and the 'double' needle instruments, in which the signals were made by
the successive deflections of the needles. Of these, the single - needle
instrument, requiring only one wire, is still in use. The development of the telegraph may be gathered from two facts. In 1855, the death of the Emperor Nicholas at St. Petersburg, about one o'clock in the afternoon, was announced in the House of Lords a few hours later. The result of the Oaks of 1890 was received in New York fifteen seconds after the horses passed the winning - post.
In
1841 a difference arose between Cooke and Wheatstone as to the share of
each in the honour of inventing the telegraph. The question was
submitted to the arbitration of the famous engineer, Marc Isambard Brunel,
on behalf of Cooke, and Professor Daniell, of King's College, the
inventor of the Daniell battery, on the part of Wheatstone. They
awarded to Cooke the credit of having introduced the telegraph as a
useful undertaking which promised to be of national importance, and to
Wheatstone that of having by his researches prepared the public to
receive it. They concluded with the words: 'It is to the united labours
of two gentlemen so well qualified for mutual assistance that we must
attribute the rapid progress which this important invention has made
during five years since they have been associated.' The decision,
however vague, pronounces the needle telegraph a joint production. If
it had mainly been invented by Wheatstone, it was chiefly introduced by
Cooke. Their respective shares in the undertaking might be compared to
that of an author and his publisher, but for the fact that Cooke
himself had a share in the actual work of invention. From
1836-7 Wheatstone had thought a good deal about submarine telegraphs,
and in 1840 he gave evidence before the Railway Committee of the House
of Commons on the feasibility of the proposed line from Dover to Calais.
He had even designed the machinery for making and laying the cable. In
the autumn of 1844, with the assistance of Mr. J.D. Llewellyn, he
submerged a length of insulated wire in Swansea Bay, and signalled
through it from a boat to the Mumbles Lighthouse. Next year he
suggested the use of gutta - percha for the coating of the intended wire across the English Channel. In
1840 Wheatstone had patented an alphabetical telegraph, or, 'Wheatstone
A B C instrument,' which moved with a step - by - step motion, and showed
the letters of the message upon a dial. The same principle was utilised
in his type printing telegraph, patented in 1841. This was the first
apparatus which printed a telegram in type. It was worked by two
circuits, and as the type revolved a hammer, actuated by the current,
pressed the required letter on the paper. The
introduction of the telegraph had so far advanced that, on 2 September
1845, the Electric Telegraph Company was registered, and Wheatstone, by
his deed of partnership with Cooke, received a sum of £33,000 for
the use of their joint inventions. In
1859 Wheatstone was appointed by the Board of Trade to report on the
subject of the Atlantic cables, and in 1864 he was one of the experts
who advised the Atlantic Telegraph Company on the construction of the successful lines of 1865 and 1866. In
1870 the electric telegraph lines of the United Kingdom, worked by
different companies, were transferred to the Post Office, and placed under Government control. Wheatstone
further invented the automatic transmitter, in which the signals of the
message are first punched out on a strip of paper, which is then passed
through the sending key, and controls the signal currents. By
substituting a mechanism for the hand in sending the message, he was
able to telegraph about 100 words a minute, or five times the ordinary
rate. In the Postal Telegraph service this apparatus is employed for
sending Press telegrams, and it has recently been so much improved,
that messages are now sent from London to Bristol at a speed of 600
words a minute, and even of 400 words a minute between London and
Aberdeen. On the night of 8 April 1886, when Mr. Gladstone introduced
his Bill for Home Rule in Ireland, no fewer than 1,500,000 words were
dispatched from the central station at St. Martin's - le - Grand by 100
Wheatstone transmitters. The plan of sending messages by a running
strip of paper which actuates the key was originally patented by Bain
in 1846; but Wheatstone, aided by Mr. Augustus Stroh, an accomplished
mechanician, and an able experimenter, was the first to bring the idea
into successful operation. Stereopsis was first described by Wheatstone in 1838. In 1840 he was awarded the Royal Medal of the Royal Society for his explanation of binocular vision,
a research which led him to make stereoscopic drawings and construct
the stereoscope. He showed that our impression of solidity is gained by
the combination in the mind of two separate pictures of an object taken
by both of our eyes from different points of view. Thus, in the
stereoscope, an arrangement of lenses or mirrors, two photographs of
the same object taken from different points are so combined as to make
the object stand out with a solid aspect. Sir David Brewster improved the stereoscope by dispensing with the mirrors, and bringing it into its existing form with lenses. The 'pseudoscope' (Wheatstone coined the term from the Greek ψευδίς σκοπειν) was introduced in 1852, and
is in some sort the reverse of the stereoscope, since it causes a solid
object to seem hollow, and a nearer one to be farther off; thus, a bust
appears to be a mask, and a tree growing outside of a window looks as
if it were growing inside the room. Its purpose was to test his theory
of stereo vision and for investigations into what would now be called
experimental psychology. In
1840, Wheatstone introduced his chronoscope, for measuring minute
intervals of time, which was used in determining the speed of a bullet
or the passage of a star. In this apparatus an electric current
actuated an electro - magnet, which noted the instant of an occurrence by
means of a pencil on a moving paper. It is said to have been capable of
distinguishing 1/7300 part of a second (137 microsecond), and the time
a body took to fall from a height of one inch (25 mm). On
26 November 1840, he exhibited his electro - magnetic clock in the
library of the Royal Society, and propounded a plan for distributing
the correct time from a standard clock to a number of local timepieces.
The circuits of these were to be electrified by a key or contact maker
actuated by the arbour of the standard, and their hands corrected by
electro - magnetism. The following January Alexander Bain took
out a patent for an electro - magnetic clock, and he subsequently charged
Wheatstone with appropriating his ideas. It appears that Bain worked as
a mechanist to Wheatstone from August to December, 1840, and he
asserted that he had communicated the idea of an electric clock to
Wheatstone during that period; but Wheatstone maintained that he had
experimented in that direction during May. Bain further accused
Wheatstone of stealing his idea of the electro - magnetic printing
telegraph; but Wheatstone showed that the instrument was only a
modification of his own electro - magnetic telegraph. One
of Wheatstone's most ingenious devices was the 'Polar clock,' exhibited
at the meeting of the British Association in 1848. It is based on the
fact discovered by Sir David Brewster, that the light of the sky is polarised in
a plane at an angle of ninety degrees from the position of the sun. It
follows that by discovering that plane of polarisation, and measuring
its azimuth with respect to the north, the position of the sun,
although beneath the horizon, could be determined, and the apparent
solar time obtained. The clock consisted of a spyglass, having an icol (double - image) prism for
an eyepiece, and a thin plate of selenite for an object - glass. When the
tube was directed to the North Pole — that is, parallel to the Earth's
axis — and the prism of the eyepiece turned until no colour was seen, the
angle of turning, as shown by an index moving with the prism over a
graduated limb, gave the hour of day. The device is of little service
in a country where watches are reliable; but it formed part of the
equipment of the 1875 - 1876 North Polar expedition commanded by Captain Nares.
In
1843 Wheatstone communicated an important paper to the Royal Society,
entitled 'An Account of Several New Processes for Determining the
Constants of a Voltaic Circuit.' It contained an exposition of the well
known balance for measuring the electrical resistance of a conductor,
which still goes by the name of Wheatstone's Bridge or balance, although it was first devised by Samuel Hunter Christie, of the Royal Military Academy, Woolwich, who published it in the Philosophical Transactions for
1833. The method was neglected until Wheatstone brought it into notice.
His paper abounds with simple and practical formula: for the
calculation of currents and resistances by the law of Ohm.
He introduced a unit of resistance, namely, a foot of copper wire
weighing one hundred grains (6.5 g), and showed how it might be applied
to measure the length of wire by its resistance. He was awarded a medal
for his paper by the Society. The
same year he invented an apparatus which enabled the reading of a
thermometer or a barometer to be registered at a distance by means of
an electric contact made by the mercury. A sound telegraph, in which
the signals were given by the strokes of a bell, was also patented by
Cooke and Wheatstone in May of that year. Wheatstone's remarkable ingenuity was also displayed in the invention of cyphers. He was responsible for the then unusual Playfair cipher, named after his friend Lord Playfair.
It was used by the militaries of several nations through at least World
War I, and is known to have been used during World War II by British
intelligence services. It
was initially resistant to cryptoanalysis, but methods were eventually
developed to break it. He also became involved in the interpretation of
cypher manuscripts in the British Museum. He devised a cryptograph or
machine for turning a message into cypher which could only be
interpreted by putting the cypher into a corresponding machine adjusted
to decrypt it. In 1840, Wheatstone brought out his magneto - electrical machine for generating continuous currents. On 4 February 1867, he published the principle of reaction in the dynamo - electric machine by
a paper to the Royal Society; but Mr. C.W. Siemens had communicated
the identical discovery ten days earlier, and both papers were read on
the same day. It afterwards appeared that Werner von Siemens, Samuel Alfred Varley,
and Wheatstone had independently arrived at the principle within a few
months of each other. Varley patented it on 24 December 1866; Siemens
called attention to it on January 17, 1867; and Wheatstone exhibited it
in action at the Royal Society on the above date. |