Class X.]

BRETT’S, LITTLE'S, AND SIEMENS AND IIALKKE’S TELEGRAPHS.

21)3

Mr. Dering considers—

I. The steel best suited for the electric magnets is thatemployed to form the balance-springs of watches.

II. As regards the mode of suspension for singletelegraphic needles, instead of suspending the needle in around hole by a round pivot in the middle, or nearly so,Mr. Dering finds it in all cases better in practice touse a triangular-shaped hole at the upper end of theneedle, with a round pivot on which to suspend it.This allows freedom of motion quite sufficient, whilst itentirely checks vibration. The instrument on this prin-ciple exhibited, shows the great rapidity in the change ofplace of the needle combined with freedom from vibration.

III. By a peculiar arrangement of coils for producingmotion in telegraphic needles, with the same number ofconvolutions, the total length of wire is lessened, and thusthe battery force required is diminished.

IV. In the apparatus for the transmission of secretmessages, by throwing stations out of the line of commu-nication, there is a means provided of instantly restoringthe revolving discs at any moment desired, and from anyposition, to the starting point.

V. In case of a telegraphic needle being deflected bythe aurora borealis, or other slight atmospheric influence,Mr. Dering places in the circuit of the line-wire a batteryof sufficient force (regulated by the number of gal-vanic elements) to counteract the disturbing influence,and thus restore the needle to its ordinary position ofequilibrium.

VI. An instrument for protection against atmosphericelectricity is also exhibited, as described under the eighthhead of specification in Mr. Dering's patent. In this thesize of the balls may be increased to any extent, providedtheir distance from the opposed plates be in a proper pro-portion diminished.' This would prevent the chance ofthe destruction of any part of the safety apparatus.

The Jury considered Mr. Dering as deserving of veryHonourable Mention for the great ingenuity lie has dis-played in these inventions.

Bkktt (No. 422, p. 455) lias exhibited a patent electrictelegraph alarum-hell, bell-handle, and battery. Thevarious letters or numbers represented on the face of thedial of the electric telegraph are made by the motion ofeither or botli of the indicators, the number of whichmotions for eacli letter or number is defined by thefigures on the centre of the dial, commencing at alltimes with the indicator on the side next the letter ornumber, and when both indicators are used, finishingwith the opposite one. The helices being double and ofa circular form, the greatest amount of electricity is con-centrated in their centre, and the magnet being in theform of a ring or horse-shoe, suspended in the centre ofthe helices, its poles are acted upon by the maximumamount of force, by which great certainty is attained, andthe magnet is deflected to the right or left according to thedirection taken by the current. The poles of the magnetbeing equidistant from the earth, the magnet is renderedstatic, and is not affected by terrestrial magnetism.

Little (p. 455) suspends a common sewing-needlewithin a tube containing alcohol by means of a perma-nent magnet at the upper end, so that it can deflectwithout friction, and does not jar against the electro-magnetic coil on either side which deflects it, while thepermanent magnet keeps up the magnetism of the needle.

Alexander (No. 426, pp. 455, 456) exhibits a modelof an electro-magnetic telegraph, described in the Ulus- |trated Catalogue. It is interesting as representing anearly development of the idea of a needle telegraph. It ;has 30 line-wires, 30 galvanometers, and 30 needles ; the jlatter carrying each a paper-screen, which, when moved, junveils a letter, &c. The galvanometers are not ealeu- !lated for actual work in real practice ; and, as only onewire is used as a return wire, common to all the galvano- !meters, there must follow a distribution of electricity 1among the rest of the wires, fatal to real signalling. !The earth is the return circuit in all practical plans. i

Smith (No. 424, p. 455) exhibits a comic electric tele-graph. This is a three-wire telegraph, and the author |considers that, by three combinations, all that is necessary ;in telegraphic communications can be performed. ’ I

McNair (No. 421, p. 455) exhibits specimens ofelectric-conducting wires for subaqueous purposes. Theprocess of making this wire is by first placing a coatingalternately of gutta-percha, or caoutchouc, and braidingof cotton-thread, till the cumulation is of a given thick-ness: after which it has an outer coating of gutta-percha,and is then placed down a hollow mandril, and by meansof a great hydraulic pressure, a lead covering is placedaround it, embracing it so firmly that the whole is onecompact body. This article seems to answer its purposewell; and, although there were many specimens of sub-aqueous wire in the Exhibition, yet, for the most part,their base is Mr. McNair's wire.

Wiushaw (No. 419, pp. 454. 455) has exhibited well-made gutta-percha tubes, furnished with ivory mouth-pieces, useful for talking across rooms, or in a railwaycarriage, or for deaf persons: an early specimen of gutta-percha tubing and lathe-bands: submarine, insulatedelectric copper wire, covered with gutta-percha, braidedwith linen, and painted or varnished. These specimenswould not hear the wear and tear incident upon theknocking about they would meet with. A long wooden| box, to be used as a battery protection : a private codebox—this is a box with a sloping front perforated withslits; letters are arranged vertically on the side, andhorizontally on the top. Within the box are as manyrollers as there are slits in front, around which arewrapped long bands of paper, eacli having a comniunica-| tion printed thereon, and repeated many times. Thej end of eacli band projects so that it may be easily drawn| out. By looking at the two letters corresponding with: those sent from the Telegraph Ofiice, the communicationI is at once discovered. A model to illustrate the hydraulici telegraph. The hydraulic telegraph was invented in theyear 1837, and from that time there have been several! modifications ; some have been furnished with floats and in-dexes carrying letters, &c., some with floats and metal-rods,which, on being either elevated or depressed, point toletters, &c. A reservoir for the supply of the water, and atank for the waste are required at eacli station. In themodel exhibited, a syphon-tube shows the application ofthe water itself, which rises and falls in the tubes byopening or closing the respective cocks. Patent glasstubes, to insulate and protect the wires of the cleetric-! telegraph when placed under ground. The use of thesewould he found to be expensive, and probably, hazardous,j Patent multi-tubular pipes, of glazed earthenware,

! well-made; their use is to insulate and separate the wiresof electric-telegraphs when placed under ground. Pro-bably these would be perfectly insulated with gutta-percha wives, but, if broken, there would be some difficultyin replacing them. The desiderata are, great durabilityand great accessibility.

Wrought-iron pipes, with ball and socket joints. Thelength of each pipe is 2 feet, and allows an inclinationof about 10 degrees, forming a subaqueous chain for' protecting electric telegraph wires when under water.This arrangement seems to be good.

This completes the British portion of the exhibition ofelectric telegraphs, and from it a very good picture ofthe English systems of telegraph is presented. One outof the only two specimens which have been sent fromabroad is that of piemens and Halske , Prussian system,and which we proceed to describe:—

Siemens and IIalske (Prussia, No. 310a, p. 1067).The telegraph exhibited by these inventors is extremelyingenious, and the construction and details are very good.

It differs essentially from all others that have fallenunder our notice, in that signals are made by arresting,instead of by causing, the passage of electric force. Itconsists of three parts,—an alarum, an indicating dial,and a printing arrangement. The force is derived fromvoltaic batteries. Darnell's constant battery is employed,twenty-five pairs of which, at each station (for the bat-teries at both communicating stations act in concert', aresaid to act through about 250 miles of wire. The force,iu all cases, is made available by means of electro-magnets.And first, in respect to the arrangement, when no com-munications are passing, but the stations are each in acondition to receive notice that they are required to attend.