Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph

English physicist and inventor Charles Wheatstone is best known for his work on the Wheatstone bridge and mass adoption of the telegraph.
Christopher McFadden

Sir Charles Wheatstone was an English physicist and inventor of many devices during the Victorian period. Amongst these included the first commercially successful telegraph, English concertina, stereoscope, and the Playfair cipher.

He is most famed for his contribution to the development of the Wheatstone bridge for measuring electrical resistance.


Although this is usually associated with Charles Wheatstone it was actually invented by Samual Hunter Christie. But it was Wheatstone who successfully popularised it. 

Charles Wheatstone was born on the 6th February 1802 in Gloucester, England. He would be appointed as professor of experimental philosophy at King's College, London in 1834.

This was the very same year he devised his revolving mirror experiment to measure the speed of electricity within a conductor. 

In 1837, with Sir William Fothergill Cooke, Wheatstone would also patent an early form of the telegraph.

Charles would also develop his own inventions ranging from musical instruments like his concertina (a type of accordion) to the stereoscope which was a device used to give depth to images.

Charles Wheatstone would also initiate the use of electromagnets and electric generators and also developed his own cipher, the Playfair cipher. Charles was knighted in 1868 and died in Paris in 1875.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Charles Wheatstone in later life. Source: Scewing/Wikimedia Commons

Early Years

Charles Wheatstone was born in Barnwood, Gloucestershire on the 6th February 1802. His father was a shoemaker who had some connections with the music industry.

Four years later in 1806, the Wheatstone family moved to London where his father made musical instruments and provided tuition in playing them. 

His father's reputation quickly grew and one of his pupils was none other than the Prince of Wales' daughter, Princess Charlotte. Charles's uncle also opened a similar business on the Strand in London and he would soon join his uncle as an apprentice.

Charles Wheatstone would quickly become fascinated by acoustics and would return to his father's workshop to study it in more detail.

In 1823 Wheatstone published the results of his experiments. Soon after he would begin to make a name for himself by becoming a prolific inventor. 

One of his greatest inventions, which was later perfected, was the bellows-blown English Concertina. These are still in use today and are also still made by Wheatstone and Company

His work on musical instruments would develop into an interest that would stay with him for life. Around this time Charles also developed an interest in optics.

In 1838 Charles invented the stereoscope which was a device that provided depth to images. This device would become a very popular scientific toy of the 19th Century. 

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Charles Wheatstone's stereoscope was a very popular toy during the Victorian period. Source: Magnus Manske/Wikimedia Commons

Wheatstone's Star Rises with the Enchanted Lyre and the Microphone

In the latter half of 1821, Charles Wheatstone became known to the public at large with his invention of the "Enchanted Lyre". An example was installed at a music-shop on Pall Mall and in the Adelaide Gallery.

His lyre consisted of a lyre-shaped object hung from the ceiling by a cord that emitted the sounds of several different musical instruments. These included a piano, harp, and dulcimer. 

In reality, his lyre was a sophisticated prank sound box where the sounds of real musicians were transmitted to the box by the steel wire supporting cable. The real instruments were played out of sight and ear-shot of passersby.

Wheatstone continued his work on acoustics throughout this period with some of his results published in the Thomson's Annal of Philosophy in 1823.

Charles Wheatstone was one of the first scientists to formally recognize that sound was in fact transmitted by waves through mediums. 

He also, through his experiments, formally recognized that sound was conveyed more quickly through solid or liquids rather than air. Knowing this he began to think of ways to transmitting sound, speech or music over long distances.

Wheatstone estimated that sound should travel at around 320 km/s through solid rods and proposed a telegraph system that could transmit speech between London and Edinburgh. He even dubbed his proposal a 'telephone'.

Charles Wheatstone also worked on a device that could augment weak or feeble sounds so they could be heard more easily. It consisted of two slender rods that would transmit vibrations to both ears of the user.

This device was given the name 'microphone'.

After inventing many more devices by 1834 he had won a name for himself. This culminated in him being offered the Chair of Experimental Physics at King's College, London. 

Charles Wheatstone's first lectures were an unmitigated failure due to his hatred of public speaking. He would later confine himself to his laboratory restricting any public interactions to demonstrations only.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Wheatstone's enchanted lyre. Source: Foyle Special Collections, Wheatstone via King's College

Wheatstone Builds the First Telegraph

In 1834, Charles Wheatstone was first invited to King's College London as a professor of Experimental Philosophy. In the same year, he conducted pioneering experiments in electricity.

He also invented an improved dynamo and two devices to measure and regulate electrical resistance and current.

These would become known as the Rheostat and improved Wheatstone bridge.

Several years later he was granted permission by the College Council to build "a series of iron and copper wires in the vaults of the college for the purpose of trying some experiments in electricity on account and at the expense of the Royal Society." 

Charles Wheatstone teamed up with William Fothergill Cooke to patent a design for their electric telegraph in June of 1837. This was the very same time as the ascension of Queen Victoria. 

Fothergill was an ex-Indian Army Officer who was impressed with a demonstration of an experimental telegraphic apparatus at the University of Heidelberg.

He was so impressed by it that he decided to forego his medical studies to devote his time to commercialize the new technology.

After returning to London William Fothergill exhibited an early telegraph in January 1837.

His experiences quickly revealed his lack of scientific knowledge that led him to consult Michael Faraday and Peter Mark Roget. It was the latter who would later introduce him to Charles Wheatstone. 

Fothergill made no secret of his intentions to develop a working telegraph to make money and propositioned Charles to join forces. Charles resisted at first believing, as a man of Science, he would rather publish his findings and not capitalize on it.

In May of 1837 Wheatstone finally relented and the two men formed an official partnership.

Wheatstone provided the scientific talent whilst Cooke provided his formidable administrative skills.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Cooke and Wheatstone electric telegraph, 1837. Source: Geni/Wikimedia Commons

Wheatstone Experiments to Measure the Velocity of Electricity

Charles Wheatstone's attained great recognition for his attempt to measure the velocity of electricity in a wire. This groundbreaking experiment was to be undertaken in the basement of King's College in 1834.

His experiment consisted of a wire that was cut in the middle. This formed a gap so that a spark would need to leap across it to complete the circuit.

Each of the wire ends (and cut ends) were then connected to the poles of a Leyden jar filled with electricity. This would allow the apparatus to produce, in theory, three sparks - one in the middle and one at each end of the wire.

A small mirror was then mounted on the workings of a watch to enable it to revolve at high speed. This was to enable Charles to observe the sparks within the moving mirror. 

Each of the points of the wire was then arranged in such a way that if the resultant sparks were instantaneous their reflections in the mirror should be one straight line. 

When the experiment was conducted it was found that the middle spark lagged behind the other two.

This indicated that it occurred an instant later than the other two and that electricity did indeed travel at a set velocity.

The next step was to attempt to quantify it. This was discovered by measuring the amount of lag and comparing that to the known velocity of the mirror. 

Next Wheatstone simply needed to compare that with the length of half of the wire.

Using this method he estimated the velocity to be about 288,000 miles per second. This is significantly faster than the current known speed of light but an interesting attempt at the time.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Source: Harmonia Philosophica

Why the Telegraph Was a Game Changer

Shortly after their official partnership was formed the duo filed a patent for a five-needle telegraph.

Their telegraph, though primarily Charles Wheatstone's design was based on the electromagnetic principle and worked by passing current through a coil of wire to produce a magnetic field.

Each needle was permanently magnetized which would then be deflected by the coils magnetic field depending on the polarity of the passing current. Each needle had its own wire and could move independently of its neighbors. 

The needles were mounted on a diamond-shaped display with all but six of the letters of the alphabet. Messages were then sent by the sender pointing the needles at the desired letters.

Interestingly though each message needed to be devised in such a way to avoid the missing letters and still make sense to the receiver.

Higher and lower rows of letters were 'selected' by using pairs of needles. As each pair of needles turned together the operator would need to trace their paths and identify where they intersect. 

Trials were held for the new device in July of the same year along with a new railway between Euston and Camden. Robert Stephenson was personally involved in the tests at the Camden end of the line. 

The experiment proved the technology was a practical application for sending messages from station to station.

Wheatstone and Cooke had successfully sent a message over wires using electricity, a truly incredible feat for the time.

Despite its apparent success, railway directors were unimpressed with the new technology and asked for their removal. 

The Telegraph Changes the World

Despite their early commercial success, it would be a competitor from across the Atlantic that would ultimately win out.

Samual Morse's telegraphic apparatus would soon gain dominance worldwide after being independently developed in the United States in 1837

Morse's apparatus became the de facto standard for Europe in 1851. Only the United Kingdom with their extensive overseas empire kept the Cooke and Wheatstone system. 

Public opinion and attention for the telegraph picked up after the capture of the murderer John Tawell in 1845. This made him the first person in history to be arrested thanks to the aid of telecommunications technology.

As the telegraph network spread its effects on other industries began to tell. The telegraph has long been recognized as the technology that brought a revolution in news production and distribution during the 19th Century.

In 1851 a cable was laid between Britain and mainland Europe.

This inspired Paul Julius Reuter to move his news agency from Aachen to London. Reuter's would, as we know today, dominate the world supply of telegraphic intelligence for rest of that century. 

Cables were beginning to be laid under the Atlantic in 1866 and also to other corners of the globe.

This would ultimately lead to London becoming the manufacturing center of cables in the world. It has also been argued that the growing network of telegraphic cables contributed to the consolidation of British dominance in World Trade.

An entirely new industry sprung up that provided new work opportunities for women as telegraphic clerks. This led to long-lasting changes in society that revolutionized the lives of millions of people around the world.

Cooke and Wheatstone End their Partnership

The partnership between Cooke and Charles Wheatstone became strained in 1841.

A dispute arose between the two men over their relative share of the honor of inventing the telegraph.

Arbitration was needed to resolve the dispute and the question was submitted to the famous engineer, Marc Isambard Brunel (Isambard's father) and Professor Daniell of King's College.

The former was to argue in favor of Cooke, the latter for Wheatstone.

The result of the arbitration was to prove unsatisfactory for both parties.

They resolved to recognize Cooke for his work in publicising the technology but not its creation, and for Wheatstone the recognition of his great work in physically creating the device.

In their conclusion:-

'It is to the united labors 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.' 

By this resolution, they effectively declared that the needle telegraph was indeed a joint production. Neither party could claim greater ownership of the technology. 

Their respective shares in the undertaking might be compared to that of an author and his publisher. Despite this dispute and others that followed, the two remained partners.

Cooke would concentrate on marketing and business affairs whilst Wheatstone continued tinkering with telegraphs for many years to come.

Charles developed the first of his many types of letter-showing dial telegraphs in 1840. 

in 1841 came the type-printing telegraph; then he introduced an automatic transmitting and receiving system. Wheatstone also studied submarine telegraphy, experimenting with an actual line in 1844 in Swansea Bay.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
William Fothergill Cooke. Source: Astrochemist/Wikimedia Commons

The Wheatstone Bridge

Of all the devices Charles Wheatstone is most famed for, the first that comes to mind is one not of his creation. It was initially invented by Samual Hunter Christie in 1833 who published it in the Philosophical Transactions of the same year.

In 1843 he brought Christie's method back into the limelight after going largely ignored for a decade.

He submitted an important paper to the Royal Society in which he presented simple and practical formulae to calculate current and resistance according to Ohm's law.

Wheatstone also introduced a unit of resistance in the form of a foot of copper wire that weighed around 6.5 grams. With this, he successfully showed how it could be applied to measure the length of wire from its resistance. 

For this groundbreaking piece of work, he was awarded a medal by the Royal Society.

Also in 1843, Charles invented a piece of equipment that could be used to read the thermometer of the barometer over a distance by using electrical contacts using 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.

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Diagram of Wheatstone's bridge. Source: Erasmouse/Wikimedia Commons

Charles Wheatstone's Playfair Cipher

Charles Wheatstone also turned his hand to ciphers. One such cipher was the very unusual Playfair cipher that he devised in 1854.

It got its name from his close friend Lord Playfair who widely promoted it to his peers.

The cipher would prove to be very secure and was used by many militaries until well into World War 2.

Its long lasting success was a testament to its resistance to cryptoanalysis and Wheatstone's ingenuity.

Despite this methods were eventually devised to crack it and it was finally retired. Wheatstone was also drafted into the interpretation of cipher manuscripts at the British Museum.

His experience in this field would ultimately lead him to build a cryptograph machine that could turn messages into ciphers. These ciphers would then only be interpreted by using a corresponding machine to decode it. 

This cipher was a manual symmetric encryption technique that was the world's first digraph substitution cipher.

The Playfair technique works by encrypting pairs of letters instead of single letters as in more simple substitution ciphers that preceded it.

This encryption of pairs of letters made it incredibly hard to break as the frequency analysis used for simple substitution ciphers would simply not work.

The cipher had more than 600 possible bigrams, as compared to the 26 possible monograms in single letter substitution. 

With the advent of digital encryption devices during the Second World War, the Playfair cipher fell out of use. It is now regarded as insecure as modern computers can easily break it.


Charles Wheatstone: Last Days and Legacy

Charles Wheatstone would continue to be attached to King's College for more than 40 years. He never formally retired and ceased to draw a salary later in life.

In 1875, almost ten years after his wife's death, Charles would succumb to bronchitis whilst on a trip to Paris. He had traveled to Paris in Autumn of that year to help perfect his receiving instrument for submarine cables. 

During this time there he caught and cold that led to an inflammation of his lungs. Charles Wheatstone passed away on the 19th October 1875

Sir Charles Wheatstone: Father of the Wheatstone Bridge and British Electric Telegraph
Charles Wheatstone is buried at Kensal Green cemetery, London. Source: Justinc/Wikimedia Commons

A short memorial service was held at the Anglican chapel before his remains were brought back to the UK for burial.

He joined many esteemed colleagues in the famous Kensal Green Cemetry where he is buried very close to Isambard Kingdom Brunel. 

Unlike Brunel's grave. Wheatstone's is quite hard to find. It has also not be maintained over the years. If are ever in the area and want to pay your respects to this great man this guide should prove invaluable.

Many of his possessions, personal library, and instruments tallying over 2000 items were given to King's college in his will.