To complete a view of telegraphy in Britain between 1838 and 1868 it is necessary to review railway signal telegraphy, which was introduced and developed in Britain during the period. This technology, to be clear, was intended to manage railway traffic and to prevent accidents; and is quite different from messaging. It is inextricably linked with railway signalling where the driver of the locomotive is authorised or forbidden to proceed by substantial line-side optical signals. The commonest of these visual signals was the semaphore; flat wooden arms atop tall poles, hinged at one end to work up and down, devised by the engineer Charles Hutton-Gregory in 1841.

The concept of “telegraphic railways” was proposed by W F Cooke in 1842. Railway signal telegraphy did not change in essence from Cooke’s initial concept. In this each line of railway was divided into sections or “blocks” of several miles length. Entry to and exit from the block was to be authorised by electric telegraph and signalled by the line-side semaphore, so that only a single train could occupy the rails. Without electric telegraphy block signals could also be worked by a simple time-delay, allowing a period to elapse before the next train was permitted to enter. The catastrophic risks of this need not be elaborated.

In the first form of railway signal telegraphy the company merely used the ordinary messaging instruments at its passenger stations, as there were then only external ground-frames with the levers that worked the semaphores, rather than enclosed signal-boxes, to send and receive abbreviated messages. This had great weaknesses in that the working of the telegraph was separate from the working of the signals, and in relying on the memory of the recipient as to the state of the rails ahead of and before any traffic, the message being momentary and not permanent.

The Electric Telegraph Company from its earliest days installed line-side Wheatstone’s magnet-and-bell, the earliest acoustic telegraph, for railway signalling that worked without any batteries. In this a small magneto-electric machine, with twin coils and a lever-action, was in simple circuit with a distant electric bell to advise the signalman at the block semaphores by a series of beats. The Eastern Counties, Eastern Union, London & North-Western, Midland, South Staffordshire, York, Newcastle & Berwick and York & North Midland all used the magnet-and-bell signal. The Eastern Counties possessed forty-nine and North-Western thirty-four out of a total of 114 magnets-and-bells in 1854; it was only applied to manage isolated sections, especially tunnels and single lines of way, on all of these railways. It was known from its impressive acoustic action as the “thunder pump”.

Pressing down the lever generated a pulse of electricity to ring a bell

 

The Electric Telegraph Company’s Edwin Clark devised improvements in the signal system of the London & North-Western Railway in March 1854 with his proposals for a block system. Clark believed in, what would be called today, fail-safe operation and, unlike in the Electric company’s public circuits, continuous currents to maintain a permanent reminder of the state of the block in front of the signalman. He used two Cooke & Wheatstone two-needle telegraphs, one for each line, up and down, in two-mile sections devoted entirely to signalling. A deflection to the left indicated train on line, a deflection to the right line clear, and no current meant line blocked, which was then to be considered a danger signal. The block instrument would normally show line clear, and would be changed to train on line when a train passed. When the train left the block, the instrument would signal back as line clear. An alarm bell was used to call attention of the signalmen. The telegraph wires were looped down certain poles, where they could be cut, so that the instruments then indicated line blocked and raised alarm. Each telegraph was worked in concert with a three-position semaphore signal on a tall post to visually communicate with the train crew at the commencement of the block.

Clark’s so-called “Two-Mile Telegraph System” was installed in 1855 between Euston Square and Rugby, 83 miles, with signalling blocks actually 2½ miles in length. However there was no electrical signalling hence to Liverpool and Manchester at all, at this time. The instruments were controlled by the railway company’s signalmen at both ends of the block, not by telegraph clerks.

Railway telegraphy for traffic control and safety, for a great many years was to be based on the common single-needle instrument. Subsequently signal telegraphy went its own way with specialised instruments. New apparatus was designed by independent electrical engineers such as Edward Tyer, C V Walker, Charles Spagnoletti and William Preece. This led to the situation in 1863 where each of the nine great railway lines from London used a different electrical signal system.

By the 1860s there was a strong opinion, after a series of accidents, that using message telegraphs was not safe enough as it was open to interpretation by the signalmen. The railway companies then encouraged simpler, definitive indicators, absolute signals as to the state of the line, to show whether or not it was occupied, and having them put solely in the hands of its signalmen.

By 1868 there were four new systems in use on British railways, as well as many derivatives of the single-needle system which remained the commonest method of controlling traffic and safety. In principal each of these had a visual line-indicator element and a very simple acoustic messaging element and the instruments were installed in signal-boxes along with the levers that worked the line-side train-signalling semaphores:

Edward Tyer’s Pointer Signal Telegraph
This was the earliest dedicated railway signal telegraph, patented in 1852. It was originally used on the South Eastern Railway, but over time was adopted by several other railway companies in Britain and France. Tyer’s system was to be manufactured by the Railway Electric Signals Company at Dalston in London from 1855, which was to become later Tyer & Company. It used a single, two-position pointer for each line, derived in appearance from the familiar single-needle apparatus, but differing in stopping to the right or left until moved back when the situation changed.

The instrument in the hands of the signalman managing two lines of railway, Up and Down, had a rectangular dial with four pointers upon it; two for incoming trains, coloured red, and for out-going trains, coloured black, on the Up rails, with two similar on the Down rails, so controlling four blocks in all. There were also instruments with two pointers, one red and one black, for single lines of rail. These pointers were worked either left for Clear or right for Blocked by four push-pull stops at the base of the dial. It had a separate Bell or, as Tyer termed it, a Gong, worked by the stops for train codes and attention signalling; with beats 1 - acknowledge, 2 - passenger train, 3 - goods train, 4 - express or light engine, 5 - obstruction, 6 - testing bells.

Edward Tyer’s system was continuously developed and altered over the rest of the century to become the commonest railway signal system.

C V Walker’s Miniature Semaphore Signal Telegraph
Walker had introduced a bell telegraph between signal boxes in 1852 and that acoustic mechanism saw wide use on the South Eastern Railway. It was the first generally adopted system of electrical train control in Britain. By the mid-1860s Walker had added a visual component. This used an instrument with symbolic miniature railway semaphores on its dial face for each line of rails in each signal station operated by keys. Each had two arms, one red and one white, worked up and down by electro-magnets. The Red arm indicated the state of the inward line, from a distant station; the White arm, the line for the outward line, from the home station. There was also a Bell. When the semaphore was up the line was Blocked or occupied. When the semaphore arm was down the line was Clear. The Bell attracted the signalman’s attention and gave messages by a code of simple acoustic beats. It required just one wire without a constant current to function.

The miniature semaphore was used so that those in charge of the out-door signals and points were warned by the same signals in the telegraph instrument signals with which every railway station-master, pointsman or porter was familiar.

William Preece’s Miniature Semaphore Signal Telegraph
This also used a miniature railway semaphore, but required two instruments and a separate electric bell for each line of rail. It actually took the form of wooden model semaphore signals on twelve inch tall posts operated by small vertical lever-switches. This system was complex, necessitating four instruments for two lines of rail each with three circuits using a constant current, the latter justified by the additional fail-safe factor in multiple wires. It was used by the London & South-Western Railway from 1863.

Charles Spagnoletti’s Disc Signal Telegraph
To make signalling as clear as possible this apparatus used a red and white coloured rotating disc on a green faced dial, with a red key and a white key. Two instruments were needed; one for Up and one for Down rails. Pressing the red key caused the red-half of the disc to appear on both the home and distant stations, the key could be locked down by a cross-pin. This indicated line Blocked. Pressing the white key caused the white-half of the disc to rotate into view, showing line Clear. Like all other railway signal telegraphs this had a Bell to attract attention and sound a code for the type of traffic; it was either a separate instrument with its own key, or built into the disc instrument and worked by either of the colour keys. This was eventually adopted by the Great Western Railway, for whom Spagnoletti worked, and its associated companies in the West of England, slowly from 1863.

In addition to signal telegraphy, the railway companies in Britain and Ireland worked their own internal telegraphs for messaging as well as for signalling. Circuits were set aside for railway use with single-needle apparatus, whether Cooke & Wheatstone’s or Highton’s, in the telegraph companies’ public wires alongside the rails. These were leased of the telegraph company as part of the wayleave agreement; who undertook the maintenance of line and equipment. Messages, which reached around 300,000 a year for each of the largest companies such as the London & North-Western, the South Eastern and the Lancashire & Yorkshire by 1867, were entirely related to railway business and there was no intercommunication. The guards on trains of some companies were provided with portable single-needle instruments and batteries to allow them to access these message circuits in emergencies.