To begin our story of the switch, we must seek the origins of the electric telegraph. From this device arose the telecommunications industry, which, in turn, was the wellspring of digital computing as we know it. It came about only after many efforts over nearly a century to convey intelligence (intelligence meaning roughly what we mean by information) by electricity.
One important caveat to keep in mind as we go along, is that the men described here used categories and concepts to think about electricity that are quite different from our own. Our physics textbooks have packaged up the messy past into a tidy collection of concepts and equations, eliding centuries of development and conflict between competing schools of thought. Ohm never wrote the formula V = IR, nor did Maxwell create Maxwell’s equations.
Though I will not attempt to explore all the twists and turns of the intellectual history of electricity, I will do my best to present ideas as they existed at the time, not as we retrospectively fit them into our modern categories.
The Electrical Fluid
The phenomenon of electrical attraction was known since ancient times. In the 6th century B.C., Thales of Miletus recorded his observations on the effect of rubbing a piece of amber (elektron, in Greek) with cat fur, noting that feathers and other light objects were suddenly attracted to the amber. Little was made of this curiosity, however, for many centuries.
With the rise of the experimental natural philosophy in the 17th and 18th centuries, though, savants began paying much more attention to such oddities of nature. According to the Aristotelian worldview that dominated European philosophy through the Renaissance, only readily observable regularities provided insight into the truth of the natural world. Artificially produced phenomena could, by definition, have little to say about nature. The new experimentalists overturned this belief. Quite to the contrary, as Francis Bacon wrote in his Great Instauration of 1620:
I mean [the natural history I propose] to be a history not only of nature free and at large (when she is left to her own course and does her work her own way)… but much more of nature under constraint and vexed; that is to say, when by art and the hand of man she is forced out of her natural state, and squeezed and moulded. …the nature of things betrays itself more readily under the vexations of art than in its natural freedom.
The English philosopher William Glibert was the first to coin a term recognizing that the ‘vexation’ of amber was only part of a more general phenomenon. In his 1600 treatise On the Magnet, he called this phenomenon electricitus, “behaving like amber”. He expounded on many other substances that had the power of attraction when rubbed, including gemstones, glass, and sulfur. Still hewing to the ancient model of matter as a composite of the four elements of fire, air, water, and earth, Gilbert believed it was the watery part, or “aqueous humor”, of these substances that gave them their electric power. 1 He did not imagine, though, that that power could ever be used as a means of communication. The attractive force worked only at extremely short distances.
By the start of the 18th century, others had figured out new ways to generate electricity. They discovered that by placing their hand on a spinning globe they could build up a powerful electrical force, and even transmit it through a piece of thread. Some years later, Stephen Gray found that he could extend this transmission up to several hundred yards. 2 Other similar electrical machines followed.
By this time, savants had begun to think of electricity as a fluid that was built up and then discharged, flowing from one place to another. Unlike Gilbert, they did not believe this fluid was ordinary water, but rather some immaterial substance. Some imagined several different subtle fluids were responsible for light, magnetism, electricity; even life. Others believed there was a single aetheric fluid behind all these phenomena, which manifested itself in different ways. 3
The greatest vessel yet known for this fluid was found in 1746, with the invention of the so-called Leyden Jar (named for the town where it first found fame). This apparatus, in its fully developed form, consisted of a glass jar coated inside and out with metal foil, with a metal terminal protruding from the top that connected to the inner foil. 4
With an electrical machine connected to the terminal, it could store tremendous amounts of the electrical fluid, as if one could simply pour it into the jar. That fluid was then discharged in a tremendous shock when the terminal was linked to the outer foil.
A whole scientific sub-culture of “electricians” had by this time emerged. With the electrical generator and Leyden jar in hand, electricity was easy to experiment with, amenable to mathematical subtlety but did not require it, and (not least) made for spectacular and exciting demonstrations. Ben Franklin, most renowned of the electricians, even proposed in a letter that several such devices wired together might be used to kill and cook a turkey for dinner. He called this multi-jar configuration a ‘battery’ (by analogy to a battery of guns): 5
…a turkey is to be killed for our dinner by the electrical shock, and roasted by the electrical jack, before a fire kindled by the electrified bottle, when the healths of all the famous electricians in England, Holland, France and Germany are to be drank in electrified bumpers, under the discharge of guns from an electrical battery.
With the power of the jar at hand, it became obvious that the electrical fluid could be transmitted over longer distances, and seemingly instantaneously. Experimenters proved as much by sending shocks through a variety of media, including rivers and lakes. Especially famous were the Abbé Nollet’s demonstrations in France. He sent a shock through 180 soldiers of the royal guard; then a mile-long chain of Carthusian monks, each connected to the next by an iron wire in his hand.6 Experimentation by this time had shown that metal wires such as these provided the best medium of transmission — that they were “conductors” of electricity.
From these new tools – friction-based generators, Leyden jars, and conductive metal wire – arose the first attempts to communicate by electricity. In 1753, one “C.M.”, whose identity has never been conclusively determined, put forth in Scot’s Magazine his plan for “An Expeditious Method of Conveying Intelligence.” He described a system with one wire per letter system, with each wire ending in a ball of pith (a spongy plant material). When a charge was sent through the wire, the electrified pith would lift a corresponding piece of paper, indicating the letter. Nothing more is known of C.M. or whether his device was ever built.7
A variety of others, however, followed his lead over the next century. In 1774, Swiss philosopher George-Louis LeSage proposed a 24-wire system, similar to the one described by the mysterious C.M., with the 24 corresponding letters arranged like the keys of a harpsichord. He contemplated presenting his design to Frederick the Great, “to judge for himself of its utility”, but if he ever did so the Prussian monarch was evidently unimpressed, since we hear nothing more of it.
Twenty years later, a Spainard, Don Francisco Salvá, proposed an approach based on the human body itself – a person would hold the far end of the wire and thus receive the message quite directly when a charged Leyden jar was applied to the near end. He did not say how he would find volunteers for the task of holding a wire all day in the hopes of receiving a shock. He later built a more humane system, based on generating sparks between foils of tin, which he demonstrated to the Spanish court. 8
Similar examples from the decades around 1800 could be multiplied, to the point of tedium.
These telegraphic experimenters came from the periphery of electrical science. The Franklins, Voltas, Faradays, and others who probed deep into the nature of electricity did not busy themselves with schemes to convey intelligence. It was an age of “projectors”, men with grandiose plans, from establishing a Scottish colony on the isthmus of Panama, to realizing the ancient dream of alchemical transmutation. They were skewered by Jonathan Swift, who filled the Academy of Lagado in Gulliver’s Travels with men vainly striving to extract sunbeams from cucumbers, and other such nonsense. Blindfolding our hindsight, we could easily dismiss men like LeSage and Salvá as projectors of this sort.9 They faced a number of obstacles to a practical and efficient system:
- A reliable source. Electric machines and Leyden jars were finicky and potentially dangerous devices that could not provide a smooth flow of electrical fluid (what we would call a ‘steady current’). Moreover, in modern terms they produced very high voltage, which meant that they were very susceptible to losses on poorly insulated wire.10
An effective means for detecting a signal and translating it into language. This was a dual problem of coming up with a sufficiently sensitive detector, and a way of encoding language in that detector. Most of the electrical projectors tried in some way to directly represent letters on the far end of the wire, whether with one wire per letter or contrivances such as synchronized wheels or multiple needles to indicate the desired letter.
A conceptual framework to guide experimentation in fruitful directions. Ohm would not lay out his famous law until 1827, and it did not become known outside Germany until the 1840s. Until then it was hard to fathom why certain combinations of wire, electrical source, and detector worked wonderfully, while others failed utterly.11
In future installments, we shall see how these obstacles were overcome, over several decades, and mostly by-the-by — as a byproduct of efforts to solve entirely different problems. But first we must look at the incumbent against which all who tried to “convey intelligence” by electricity would be compared – the telegraph. For before the telegraph with which we are familiar, there was this:
- John Joseph Fahie, A History of Electric Telegraphy, to the Year 1837 (1884)
- Thomas J. Hankins, Science and the Enlightenment (1985)
- J. L. Heilbron, Electricity in the 17th and 18th Centuries (1979)
- E.A. Marland, Early Electrical Communication (1964)
- Gilbert, On the Magnet, trans. by P. Fleury Mottalay (1893), 74-85; J. L. Heilbron, Electricity in the 17th and 18th Centuries (1979), 169-79. ↩
- Hankins, 58-61. ↩
- Hankins, 50-53; Heilbron 67-71. This remained the dominant model until Michael Farady’s fields, conceived in the 1830s but not widely accepted until much later. Bruce J. Hunt, Pursuing Power and Light (2010), 77-79. ↩
- Hankins, 67-69. Originally the jar was simply a jar of water with a metal object placed in it. ↩
- Ben Franklin on Cooking Turkey… with Electricity, accessed November 25, 2016. Likewise the term ‘charge’ is by analogy to firearms. Heilbron provides estimates of the power of 18th century electrical equipment in modern terms (82-83). ↩
- Extract of a Letter From Mr. Tubervill Needham to Martin Folkes, Esq.; Pr. R.S. concerning Some New Electrical Experiments Lately Made at Paris (1746) ↩
- E.A. Marland, Early Electrical Communication (1964), 17-19. ↩
- John Joseph Fahie, A History of Electric Telegraphy, to the Year 1837 (1884) , 89-91, 101-108. ↩
- Jonathan Swift, Gulliver’s Travels (1726), pt. 3. ↩
- Marland, 29. ↩
- Marland, 50. ↩