Class X.] BRETT’S ELECTRIC PRINTING TELEGRAPH, TOCKET COMMUNICATOR, &c\ 289

only in one direction. The magneto-current employed jactuates electro-magnets, the armatures of which carry jthe index-needle, and move it as they move. These ‘currents do not need so good insulation as do batterycurrents.

A Council Medal was awarded to Mr. Henley.

J. Brett (No. 429. p. 458) exhibits an electric printingtelegraph, which consists of two parts, called by Mr. Brettthe communicator or key-board, and the printing machine;the former is supposed to be at the station from whichintelligence is to be transmitted, and the latter, the placeto which it is to be sent.

The machinery is propelled chiefly by the power ofweights, or by ordinary clock-springs. The motion of jthe printing-machine is regulated by the galvanic current, jby means of an escapement, and which requires muchless power than is necessary to impel the machinery; thus *both the advantage of the instantaneous action of the jcurrent, and the greater power of the weights, combineto accomplish the work for which this machine isdesigned.

The key-shaft is about five inches in length; thefiuger-kevs act upon pins by means of rods and levers.The circuit-wheel is fixed to the axis of the key-shaft,which works upon a hollow axis with ratchet-wheels andclicks, so as to move forward in one direction with thecircuit-wheel. Immediately after it lias revolved thedesired distance, a number of points, to correspond to theletter or character indicated by the finger-key, andrequired to be printed by the printing-machine, arereleased and return to zero, by means of a pulley andweights, independently of the circuit-wheel. The type-wheel is so attached to the key-shaft that a message maybe printed in duplicate.

There is another arrangement by which the type-wheelor wheels is attached to a hollow axis, which carries thetype-wheel backwards or forwards by a pinion acted uponby a train of wheels in connection with it: this traincommunicates motion to an arbor, to which a disc is fixedfirmly: against the disc a ratchet-wheel is placed, mountedloosely on the arbor, between a fixed washer, and adjustedby a spring-catch, so that it can turn a short distance onlyon its axis. A slot is cut in the disc of this ratchet-wheel,and also through the adjoining disc, in which a pin works,connected with the tail of a click ; this click is so adjustedas to catch into the teeth of the ratchet-wheel. Therefore,when the click is locked into one of the teeth, it causesthe type-wheel to travel with the axle and pinion; butwhen the click is released, the type-wheel returns to zero,by the assistance of a pulley with cord and weight, or ofa spring connected with the hollow axis. A lever is putinto action by a pin attached to the common wheel of theprinting train of wheels, and by its means the type-wheelis returned to its starting-place immediately after a letteror sign has been printed. Mr. Brett considers thisarrangement very important, as it insures safety from thederangement to which the type-wheel, by a continuousstep-by-step movement, is liable, on account of the accu-mulation of errors, arising either from atmospheric orother causes. From the momentary effects of lightningor atmospheric influence the machine immediately correctsitself, aud the sense of the subsequent correspondence isnot disturbed.

The train of wheels which give motion to the type-wheel is controlled by means of a secondary train ofwheels, fixed to the back of the frame-plate, whichcontrols and reduces the force of the escapement, andrelieves the galvanic or magnetic power required for its !regulation. I

The type-wheel upon this arrangement may have any !desired number of letters and characters without retarding ;the operation, as they would be so economically placed in jthe order fitted for their general application. Mr. Bretthas adopted an arrangement of letters on the type-wheel *in the order of frequency of occurrence. The arrangement jis as follows:— e, t, a, o, «, s, //, r , u', l , c, f f in , e, n, j

6 , (J , }),jy Ify k , Vy Xy ^ , Z. \

In Mr. Brett's patent of 1S45 the key-shaft was workedby means of a bevelled friction-wheel, set in motion by atrain of wheels and a weight. The barrel was made the

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length suited to the number of the finger-keys, and thepins were fixed in a uniform helical row, extending itsentire length. In the arrangement exhibited, the circuit-wheel is fixed to the end of the key-shaft, as before stated.Connected with this wheel are two pieces of metal, whichform the conductors of the current; one of those restsupon the periphery, and the other upon the collar of thecircuit-wheel, being alternately upon one of the teeth andover one of the spaces. Whilst resting on the tooth itcompletes the circuit, and when over a space the circuitis broken, and soon alternately.

In connection with the printing train of wheels of theprinting-machine, is an eccentric or cam-wheel, whichrevolves upon the shaft, and is connected with an hy-draulic regulator; so that when a piston is raised by therevolution of the type-wheel, a partial vacuum is formedin the valve-chamber, and water passes through holesinto the chamber, and momentarily takes off the deadweight of the piston, aud some of the friction of the lever,from the escapement. On the type-wheel being arrested,a lever descends, releases the cam-wheel, and the paperis pressed against the letter upon the type-wheel.

Plumbago or vermilion is preferable in use to printing-ink, as it does not require replenishing for a considerabletime.

Mr. Brett also exhibits a small instrument which hecalls a pocket communicator, designed for the use ofguards of railways, to communicate with the neareststation on the occurrence of accidents, or on assistancebeing required. In use it is placed in connection with thelines on the railway, and a galvanic battery on thetender, the wheels of the carriage completing the circuit.

It consists of au axle, to which is fastened a ratchet-wheel, over which is fixed a circuit-wheel, with teeth andspaces suited to the number of letters and charactersrequired. On its face is placed another ratchet-wheel,which causes the circuit-wheel to rotate when the click isput into operation, by moving forward a handle, connectedwith which is a pointer, by which the letters or signs arcpointed out.

The arrangement admits of a double circuit-wheelbeing employed, for the purpose of reversing the poles ofthe battery, and thus changing the direction of the currentof electricity.

An electric circuit regulator is also exhibited byMr. Brett. Its purpose is to give a controlling power overall the stations on any line of electric telegraph, so thatany important telegraphic information could be trans-mitted to one or more distant or intermediate stations,without the knowledge of such communication transpiringto any other place than the one intended : the otherstations on the line being put out of circuit for the time,by means of a separate wire in connection with a verysmall apparatus at the different stations. This apparatusit is necessary to construct with a full knowledge of thenumber and relative importance of the stations upon theline, for the purpose of making the calculations correctly :it will be necessary to exemplify this. Take, for example,five stations,—London, Dover, Calais, Amiens, and Paris ;and suppose the remaining stations to indicate upon thedial a universal communication with all the live stations.Ten other divisions will give all the changes of onestation to another, thus:—London to Paris, London toDover, London to Calais, London to Amiens , Calais toAmiens, Calais to Dover, Amiens to Dover, Paris toDover, Paris to Calais, Paris to Amiens and London ,Calais and Paris ; making in all twelve points or changes.At each of the stations should be a small apparatus havinga dial, similar to a watch, having indicated upon it thenumber of points, or the names of the respective stations.At the number indicated a small hand or pointer wouldshow that station which was engaged with another in theoccupation of the line, as all these would be acted uponsimultaneously ; and thus any unnecessary interruptionwould be prevented.

By the use of Mr. Brett’s telegraph, communicationsare made in any language, and printed upon paper withconsiderable rapidity and precision ; thepaper and ink arcself-supplying, and sufficient may be placed in the appa-ratus of both to last for some time. Mr. Brett says, tiiat

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