The Telotype: a Printing Electric Telegraph

Francis Galton
John Weale, 1849 (post-dated: June, 1850)

PDF Facsimile  (~1.6 Mb) by
(with kind permission of the Linda Hall Library, Kansas City, MO).

This was Galton's first published work, and is now exceptionally hard to find.  The edition presented here is a revised edition, as there is an earlier version printed by "J Ridgeway" rather than John Weale, dated 1849, containing fewer illustrations and less text (this may have been a proof copy).

When it was distributed, Galton was abroad on his expedition to South-West Africa, and he believed that it went unnoticed.  However, it was noticed, e.g. in the influential periodical The Athenaeum [No. 1218; March 1,1851;  245] where it was favourably (if only briefly) reviewed (anonymously, but the reviewer is now known to have been William Hepworth Dixon).  Unfortunately, the Athenaeum misidentified the author as Francis Gulston.  There were probably other reviews too, since little escaped the Victorian periodicals.

Since this booklet has long been extremely difficult to locate, let alone read, it is not commonly realized how substantial it is, and how much work Galton must have put into researching it and performing the experiments that preceded it.  This throws some light on Galton's "fallow years" (1844-1849), which were perhaps not as fallow as Karl Pearson supposed.

The "Telotype" that Galton described was to be a printing needle telegraph, which printed real characters rather than the dot-dash marks used by Morse-like devices.  From the text it is clear that parts of this device were constructed, but the whole device was never put into production.  By the late 1840s, working telegraphs using a precursor of what is now called Morse code had rapidly spread, especially in the United States, but printing telegraphs were less common, and were based on a different principle (requiring a much stronger electrical signal which would break or complete a circuit on the remote machine). 

"There  is probably no branch of practical science in which a real improvement would be hailed with greater pleasure than that of Electro Telegraphy. A great deal has been done but very much more is wanted before Telegraphs can become the common, even household, instruments of communication that they probably are destined to be. 

In all those now in use the art of transmitting and interpreting messages requires much time and practice for perfect acquirement. The superior advantages of a telegraph capable of printing messages in the ordinary alphabetical characters is obvious, but it is, in the first instance, a problem of some difficulty to govern machinery of the requisite power by the extremely feeble force of which we have to dispose. 

To effect this is, in part, the object of the instrument described in the following pages. By the methods here explained it is hoped that a printing electric telegraph may be constructed, simple in its mechanism, easy to be worked, and equalling in its sureness and speed any of the forms of telegraph now in use. In the Telotype (as our instrument may be termed), by merely touching a key on which any letter is marked that letter is to be printed, almost instantaneously, at the opposite end of the line." (page 1)

Galton's device used three needles, each with three possible positions: l=left, o= neutral, r=right.  This ternary (as opposed to binary) code could represent 27 characters (3 cubed), and Galton proposed doubling it by using two-character sequences to represent not only all punctuation and special characters, but also to effect mechanical actions remotely, such as ringing a bell.  The device was to be powered mechanically in its own right, with the (relatively weak) electrical signals received deflecting needles which produced their effect through an electrical-to-mechanical transmission system of interacting needles and rods. 

An operator was to send messages by typing on the local telotype, using keys marked with alphabetic letters, resulting in transmission of electrical signals to the remote telotype, which would ultimately print out the letters sent, without requiring a manual "decoding" stage. 

This should be contrasted to the Morse telegraphy system, which then recorded dots and dashes for later decoding, a step which was later eliminated in favour of real-time decoding of audible signals by a skilled operator trained by ear (Galton would have been intrigued to hear that this role was unusually well-suited to women).  Morse invented none of this, which was pioneered largely in Europe much earlier, but he was successful in obtaining the US patents (which helped to enrich his astute partner Ezra Cornell to the extent that he could retire and found Cornell University in Ithaca NY). 

Since the telotype did not require operators to decode signals, Galton ambitiously envisioned widespread installation of the machine in residential houses and businesses connected to branch exchanges.

"If telegraphs, that worked and printed satisfactorily were once found practicable, most large houses, public and private, would soon become supplied with them. The communication being so immediate, answer following question as soon as it is put, affords much more nearly the advantage of a personal communication than the best regulated post office ever could. Any scheme to introduce telegraphs generally, would probably be first confined to London. There would be central offices, and from these bundles of wires would radiate to numerous branch offices; from the branch offices again wires would pass along the adjacent streets, and supply houses as they passed. The expense of distributing wires in this way could not be extreme, for, if the branch offices were as numerous as the branch post offices now are, the distance that the wires to each private house would have to traverse would never be great".  (page 32)

This eventually happened, in the form of the fax machine and later the internet, over a century later. As it was, Galton was far ahead of the enabling technology he needed.  Reliable and durable insulators had yet to be invented, though many were being tried at the time, and the leakage from lines would have disturbed any large-scale deployment as soon as the effects of the weather took hold.  It is also questionable how reliable Galton's complex arrangement of interacting needles and rods would have proved over time, without constant maintenance.  Of course, these are the sorts of practical difficulties that telegraphy in general had to solve over time, through hard experience

Most interestingly, Galton also described a built-in encryption mechanism for sending encoded messages using a key, which could be made increasingly secure by extending the length of the key used.  This may have been the very first attempt to design an automatically encrypting printing telegraph:

"If the wires on leaving the contact keys were, any of them, crossed ... it is obvious that signals passing through them would appear totally different at the distant station to what they were at the near one; but if the wires were again crossed (re-reversed) at the distant station, then the signals would be put right again and become intelligible. In this way two telegraphs might evidently correspond freely with one another, while an interposed telegraph could not understand the messages that were conveyed through it. ...

By increasing the number of "crossings" effected by his "cypher-slides", Galton proposed making a brute-force attack on the cipher more difficult, at least for the manual calculations that would then have been required:

Lastly, as to the best number of cypher slides to use. If we have two, there are 8x8 or 64 different ways of adjusting the two instruments; if three, 64 x 8 or 512; if four, 4,096, or very near 5,000; and therefore, if five, 40,000. We should prefer this latter number; it is to all practicable purposes perfectly secure, while four slides would hardly be so.

In some important respects this was a precursor to modern computers, insofar as these are used for information encoding and communication  (Galton would later befriend the computing pioneer Charles Babbage, who along with Charles Darwin signed his certificate of induction into the Royal Society in 1856).

Galton, in his characteristically modest way, recalled in Memories of My Life (pp. 119-20):

"I had always a liking for electricity, and had some cells in a drawer of my study table with wires leading from them through the woodwork, to which apparatus could be attached. All this would be thought very elementary now, but some new things have to be done by such means when a science is in its infancy. I wished to print telegraphic messages and to govern heavy machinery by an extremely feeble force.

Suppose a telegraphic needle of the most delicate construction conceivable, having the three possible movements of right, neutral, left, to be momentarily lifted off its support by an arm that squeezes it against a little cushion above. However delicate the needle may be, its projecting ends will be stiff enough to push another freely suspended (but non-magnetic) needle of a much stronger and heavier build, in the same direction as itself. This process may be repeated on a third needle of considerably larger size and greater strength ; and if desired, on a fourth. The force required to keep all this going is independent of that which moves the first needle, and is applied by a reciprocating beam worked by ordinary power. The synchronising of the two stations is a simple matter, no great precision being wanted in order that the electric impulses should be delivered to the first needle at the right times. Without going further into this long bygone matter, I may say that I printed what I had to tell in a pamphlet entitled The Telotype .... The pamphlet was post-dated, after the manner of some publishers, as being in June 1850. It was really printed in 1849; I had left England for my travels on April 5, 1850. The pamphlet had long since gone into the limbo of the forgotten, so it was a surprise to me, not many years ago, to meet one of the most prominent electricians of the day, who told me that he had seen and procured it for the library of the Electrical Society. Moreover, he spoke appreciatively of my youthful attempt. Requiescat in pace."

Communication over distances was one of Galton's enduring interests, and his restlessly inventive mind often returned to in different contexts.   In a letter to The Times he described how shipwrecked sailors might attract attention over considerable distances with improvised sun-signals.  He devoted a great deal of attention to the use of heliographs, directed using a view-finder device he invented, for communication using sun signals.   His heliograph design was manufactured and used successfully in the field.  Later, he would even propose the use of sun signals for inter-planetary communication, and devise a scheme for numerically encoded facial profiles of criminals, which could be transmitted cheaply and efficiently by telegraph.