1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



vented the plan from being practically applied, and the expense 

 would have been a serious obstacle. 



The correctness of the principle having been fully ascertained, at- 

 tention was directed to render it available by arranging the needles in 

 such manner that any two of them could act simultaneously, and thus 

 produce a greater number of signals with a much reduced number of 

 wires. In 1840, an electric telegraph of this kind was constructed on 

 the Great Western Railway, for a distance of twenty miles, by Messrs. 

 Cooke and Wheatstone. Five needles were employed on that tele- 

 graph ; they were arranged on a diagonal dial, whereon the letters of 

 the alphabet were painted, so that any two of the needles might be 

 made to point to the letter required to be indicated. In subsequent 

 improvements, the conducting power of the earth was rendered avail- 

 able fur the return-current, and by other contrivances all the signals 

 may be made with only three wires. This was a great advance on 

 the earlier attempts at electrical communications, and if nothing 

 farther had been accomplished, the advantages of this system of tele- 

 graphing were sufficient to ensure its ultimate adoption. Within the 

 last two years, however, the progress of invention has brought elec- 

 trical communication to such perfection that, by means of one wire 

 alone, and without an artificial voltaic battery, any signal between 

 distant places can not only be indicated, but actually printed at both 

 stations simultaneously. There are two claimants for the honour of 

 the invention of the electro-magnetic printing telegraph, but into the 

 merits of their respective claims we have no desire to enter. Pro- 

 fessor Wheatstone and Mr. Bain, a watchmaker from Scotland, are the 

 disputants, and each contends that the other has appropriated his 

 ideas, though the mechanism of the two is not alike. The telegraph 

 of Mr. Bain has this advantage over the telegraph of Professor Wheat- 

 stone, that it does not require the agency of any other electrical force 

 than the natural electricity to be derived from the moisture of the 

 earth. 



It had been known for some years that a sensible degree of elec- 

 tricity may be developed by connecting different metallic veins, and 

 Mr. Bain has further discovered that by placing plates of zinc and of 

 copper underground, and connecting them by an insulated wire, a 

 constant current of electricity is excited sufficient for working the 

 telegraph of his construction. By this means the uncertainty, trouble, 

 aud expense of a voltaic battery is avoided, the actuating power is 

 derived from the earth itself, and the telegraph may be worked by a 

 single wire. We shall proceed to explain the modus operandi of this 

 self-actuating telegraph, and without pronouncing an opinion respect- 

 ing the comparative merits of the two competing electro-magnetic 

 printing telegraphs, we shall be able to show that Mr. Bain's, at least, 

 exhibits great ingenuity and vast inventive resources, and that it is 

 capable of being extensively applied to the most important uses. 



The annexed woodcut represents the apparatus in all its parts, an 

 exact counterpart of which is to be placed at the distant station with 

 which it is to communicate. F is a main-spring barrel acting on a 

 train of wheels, G, H, I, which turn the balls of the governor K, and 

 the hand B, of the dial A, B, C, whereon the requisite letters and 

 figures are engraved. It will be observed, that the motion of the 

 wheels is stopped by the arm E, which catches against the lever 

 affixed to the arbor of the wheel I. To set the machinery in motion, 

 therefore, it is necessary to remove the stop E from its bearing on the 

 lever, and this is done by electrical agency in the following manner : — 

 A- is a coil of wire twisted round a light hollow frame of wood, and 

 freely suspended on a centre. B-' is a powerful permanent magnet, 

 fixed within the coil ; and C- C-" are sections of similar magnets. D 2 

 is a spiral spring connected with the source of electricity, buried 

 underground, which leaves the coil free to move when the current of 

 electricity passes through it, and brings it back to the original posi- 

 tion when the electric circuit is broken. The peculiarity of this 

 arrangement is, that the coil of wire is deflected instead of the magnet, 

 by which deviation from the usual action, the deflecting force is ren- 

 dered more energetic. The metal hand of the dial is connected with the 

 deflecting coil, but it is insulated from the dial itself, the latter being 

 in metallic connection with the wire laid down between the two 

 stations, which serves to complete the electric circuit. When a metal 

 pin is inserted into any one of the holes marked on the dial, the hand 

 is stopped by pressing against it, and the metallic communication is 

 then completed. The electricity thus passing through the coil of wire 

 deflects it into the position represented in the woodcut — its natural 

 position, towards which the spring D tends to carry it, being inclined 

 upwards in the direction of the arrow. When the metal pin is re- 

 moved, aud the electric current is thus broken, the spring carries the 

 end of the coil upwards, by which action the arm E relieves the 

 lever, the train of wheels is set in motiou, and they continue moving 

 until the electric circuit is renewed by again inserting the metal pin 

 into the dial. The type wheel L, on 'the arbor of the wheel H, is su 



adjusted, that when the hand of the dial is stopped at any letter, a 

 similar letter is presented opposite to the small cylinder M, whereon 

 the paper for receiving the printed communications is fixer). By the 

 rotation of the wheels the balls of the governor diverge, thereby 

 raising one end of the lever V and depressing the other, which allows 

 the pallet I to escape, but the rotation of the arbor is still prevented 

 by contact with the second pallet u. When the electric circuit is 

 again completed by stopping with the metal pin the hand of the dial 

 opposite to the required signal, the coil of wire A- is deflected to its 

 former position, and the machinery is stopped bv the arm E. The 

 balls of the governor immediately collapse, and by 'depressing the end 

 of the lever V, clear it from the second pallet u, and allow the crank 

 spindle S (which is moved by a second mainspring in the barrel N, 

 connected with a train of wheels) to complete its revolution. The 

 motion of the crank presses the type against the signal-cylinder, and 

 a piece of ribbon saturated with printer's ink being interposed between 

 the type and the paper, the letter is distinctly printed thereon. At 

 the same time a spring z, attached to an arm of the lever y, takes into 

 a tooth of the small ratchet wheel a, on the spindle of the long pinion 

 6, which takes into and drives the cylinder wheel, so that, when the 

 crank returns to its former position, it moves the signal cylinder suffi- 

 ciently to leave space for the impression of a fresh letter. A spiral 

 motion is also given to the signal-cylinder as it turns, whereby it is 

 gradually raised to receive the succeeding lines, and the message is, 

 in fact, thus printed in one continuous spiral line. As the two appa- 

 ratus at the distant stations are exact counterparts of each other, and 

 are set in motion simultaneously by voltaic action, the hands on the 

 dials always stop at the same symbol, and that symbol is printed on 

 both at the same instant. 



The cost of an electro-magnetic printing telegraph of the kind we 

 have described, would not we believe exceed 407. per mile. It is no 

 doubt susceptible of further simplification; but, taking the apparatus 

 in its present state of improvement, it is capable of extensive applica- 

 tion, not only in transmitting information from the outports and the 

 principal centres of manufactures, to the seat of government, but also 

 for conveying intelligence from mercantile firms to their distant 

 agents and correspondents. When the facility with which instanta- 

 neous communications can be made by electro-magnetic printing tele- 

 graphs becomes better known, and the plan more extensively adopted, 

 we doubt not that public telegraphs will be established, and be con- 

 sidered as important as we are now accustomed to consider the esta- 

 blishment of a regular postage communication between all parts 

 of the kingdom. Means might be adopted, if necessary, to secure the 

 secrecy of communications thus transmitted, or the parties communi- 

 cating might agree upon cyphers, the signification of which would be 

 intelligible to none but themselves. 



Electric telegraphs have already been applied on several railroads 

 with signal advantage, and it only requires the simplification and 

 cheapening of their construction, which seems to be now attained, 

 to render their adoption on railways general. By communicating 

 from station to station the time at which a train starts, its arrival may 

 be anticipated with great exactness, and preparations made accord- 

 ingly. This is essentially necessary in the case of special trains, and 

 when the roads are undergoing repair, and, by thus forewarning the 

 approach, might be the means of altogether preventing accidents from 

 collisions. 



Electric telegraphs also present an important economical advantage 

 in the construction of railroads on lines of inferior traffic, since, by 

 their aid, the transit of the trains to and fro might be conducted on a. 

 single line of rails with equal safety as on the most costly double line. 

 As the departure of each train would be instantly signalled from one 

 station to another, there would be no danger whatever, of two trains 

 meeting ; and the times of departure from each terminus could be so 

 arranged that the up and the down train should meet at a stated 

 point where a short double line might permit them to pass. We con- 

 ceive it to be within the range of probable improvements in the 

 electro-magnetic telegraph, that the wheel of the engine, as it passes 

 along the rail, should be made to trace its course on the signal-cylinder 

 of the printing telegraph, so that the position of any trains or number 

 of trains on an extended railway might be known at a glance, and 

 each one be seen tracing its own course on the telegraph chart of 

 every station. But without waiting for further improvements, the 

 electro-magnetic printing telegraph, in the state of perfection to 

 which it has been brought by Mr. Bain and by Professor Wheatstone, 

 affords facilities sufficient to render its adoption on all railways a point 

 of duty with the directors, as such a forewarner of danger, it is 

 admitted, would prove a most valuable preventive of accidents. 



W 



