2S3
[Class X-
unlock an escapement, and cause a wheel to imitate themotion of the letter circle. This wheel brings roundtype punches, and on coming to rest, a hammer strikesthe puuch (worked by a coil-magnet), and impresses apaper ribbon, which is drawn uniformly along by clock-work.
VI. Nott and Gamble’s telegraph presents two doublealphabets; the one direct, the other inverse, and thedigits are many times repeated on a circular dial, havingan index, which moves with a step-by-step motion, andis brought to rest at the letter required. The force isderived from the voltaic battery ; and current after cur-rent is set in action by the successive depression of anivory key by the finger; it is made available by meansof two U-shaped electro-magnets, acting simultaneouslyand in the right direction upon two levers, furnishedwith clicks, which work in a scape-wheel that carriesthe index, and propel it, notch by notch, as each contactis made.
VII. Hatcher’s induced current machine, patent 1847;to produce currents in either direction by one motion ofa handle.
Two make and break circuit arcs of brass and ivory-pieces, alternating with rubbing-springs, so arranged thatwhen the springs on the right arc connect brass andbrass, that on the left shall connect ivory and ivory, andvice versa. In either state, a depression of the handleBreaks contact of coils of magnets, and throws a shockalong the wires.
VIII. Cooke’s patent, 1845. A portable telegraph,for the guard on a railway to receive messages in case ofan accident, by making a contact with the regular wiresalong the line.
IX. Brett and Little’s patent. A conventional al-phabet by needle oscillations, in which the handle at thefirst station, by working to and fro, establishes alternatecross communications, and thus directs the current alter-nately one way or other. There are two needles, buteacli needle oscillates in only one direction.
X. Wheatstone and Cooke’s patent, 1840. In thisarrangement the rapid alternation of circuits is effectedby the dial-wlieel turning a pinion, half of ivory andhalf of brass. The motion of the dial-wheel is imitatedat the second station by an escapement-wheel, driven bythe oscillation of a pair of detents worked by a four-coillocal magnet apparatus, alternately urging a piece of soft
a b c a 2 b 2
iron to and fro. It is an imitation telegraph, and readsthe actual letters.
XI. Hatcher, 1847; electro-magnet printing telegraph.The usual reciprocating action between coil-magnets, in-stead of carrying round a wheel, makes a series of dotsoil paper constituting a conventional alphabet.
XII. Bains’ patent, 1846; chemical planting tele-graph. Signals are given by marks arranged in one lineof different lengths and intervals by the pressure (onprussio-muriated paper) of a link of iron wire, which de-posits prussian-blue, the paper being adjusted by clock-work.
A Prize Medal was awarded to the Electric TelegraphCompany for the exhibition of this fine series of tele-graphs.
The British Electric Telegraph Company (No.432, p. 459) exhibit Highton’s patent, dated 1848. Theprinciple is economy of wire bj* encircling the poles of ahorse-shoe rather than going round a straight magnet.The power gained is stated to be as 7 to 1. An improve-ment is also claimed in the mode of throwing two linesinto connection by a single spring and cross bars, so as tohalve the risk of a spring breaking. Thirdly, carrying acoil all round a horse-shoe, and thus causing* each part ofthe magnet to act on each part of the coil; but this is inopposition to the first principle, so far as a saving of halfthe wire is concerned. Fourthly, application of the prin-ciple of the arrangement of the letters on the rim of adial-plate, not according to alphabetical order, but ac-cording to frequency of occurrence in writing: butarrangements of this kind have been in use in printing-offices, on the principle of the more frequent lettersbeing placed the most within reach. Fifthly, a readymode of bringing the needle on the alphabetical-dial tozero, by touching a key. The step-by-step currentwhich works the needle round is thus thrown out ofgear, and its power thrown on another magnet, creatinga force which lifts the detents of the escapement, andlets it pass round to the stop in the same direction.Sixthly, is exhibited a very ingenious piece of me-chanism for locking the printing-wheel, so that it cannotby any possibility run on two letters for one motion ofthe alphabetical needle. Seventhly, since 3 3 - 1 = 26,the number of letters in the alphabet, and since 3 3 — 1 isalso the number of electric combinations of three oscil-lating needles; thus—
c 2 a 3 b 3 c®
of which &, b 2 > b 3 is an inactive combination arising froma quiescent position of all the needles ; a conventionalalphabet may be constructed by a simultaneous use ofany three of the combinations, except b, b 2 , IP ; thus,
\\\ may indicate A; j may indicate B; and so on.
This principle is worked out by a system of crosscombinations of three batteries, acted on by keys, as in apiano. The key a being depressed brings simultaneouslyinto circuit the three positive currents; b brings intoaction the positive current of battery 1 and 2, and throwsbattery 3 out of action.
Another application of this principle to a reading alpha-bet consists of three pendulums, each carrying screens,with orifices pierced so that by each combination (bringingthe screens into twenty-seven different relative positionsbehind one another) only one orifice shall be exposed,showing the desired letter. This principle is also appliedto printing telegraphs; thus, no type can be pressed tillthree conductors conspire, and these are directed andensured by the three positions of the needles, and, whichcomes to the same thing, by the combinations of the threecurrents creating twenty-seven electro-magnets.
Highton, patent of 1850. Use of a permanent magnetto keep up the magnetism of a soft-iron moveable mag-netic needle (as a security against lightning destroyingthe magnetism of this needle), by continually re-mag-netising it. A lightning strainer is also exhibited. Thecircuit-wire, covered only with bituminous paper, ismade to pass through a box of iron filings. This is found
to be insulation enough for the galvanic current, but notfor the tension electricity of lightning, which is thereforecarried into the earth by the filings.
The use of the secondary battery, the 33 - 1 combina-tion principle, is made applicable to* printing, by touchingkeys carrying the letters to be printed; and a patentedapplication of the chemical principle, that sulphate ofalumina in solution may be advantageously used, insteadof sulphuric acid, to keep the battery in action.
A Prize Medal was awarded to the British ElectricTelegraph Company for the exhibition of their ingenioustelegraphs.
Henley (No. 428, pp. 457, 458) exhibits two powerfulcompound linear bar magnets. The electric force isproduced by a semi-rotation of a double electric coil andarmature opposite either pole. The movement is extremelysimple and neat, and the shock delivered very powerful.It has worked through 560 miles of wire, also through60 feet of water. Experiments on the Serpentine weremade, when several feet of the wire under the water werestripped of the gutta-percha coating without dissipatingthe current; and when (as the Jury were told afterwards),on further trial, the wire was divided under the water,yet the shock passed between the ends sufficiently todeflect the needle effectually.
The principle of using permanent magnets as a sub-stitute for a battery is not new. At Gottingen , in 1839,Sir John Herschel was present when Gauss telegraphedfrom his house to his observatory by its means.
This is a double-needle telegraph, but the needles move