with the cylinders and on those screws are traversing nuts. To those nuts arms are attached at the end of each of which, there is a metal style or point that presses on the cylinder, and is carried by the rotation of the screw from one end of the cylinder to the other in a given number of revolutions. On to the cylinder of one of the instruments the communication to be transmitted is placed. The message is written with varnish or other substance that will not conduct electricity, on tin foil or other conducting substance; or the tin foil may be coated with a non-conducting body and the writing be traced upon it with a point, so as to expose the metal. On to the cylinder of the corresponding instrument the paper to receive the message is fixed. This paper is thoroughly moistened with a solution which electricity will readily decompose, and thus a mark is produced on it whenever the electric circuit is completed. The solution may be of various kinds, but the one I prefer is a mixture of one-third part of muriatic acid, one-third part water, and one-third part of a saturated solution of prussiate of potass. Or the paper may be saturated with diluted acid alone, and after the message is impressed on it, it may be dipped in a weak solution of red-ferrocyanate of potass, in which case the writing will be invisible until brought out by the ferrocyanate. When a solution of prussiate of potass or of the red-ferro-cyanate is used the marking point of the receiving instrument should be of iron or steel, and it should be connected with the positive pole of the voltaic battery. The points carried by the traversing nuts are insulated from the other parts of the instruments, and are connected with one of the wires from a voltaic battery, the cylinders being in connexion with the other wire, so that the electric circuit can be completed only by passing through the point to the cylinder of each instrument. By this arrangement whenever the point of the transmitting instrument is pressing on the exposed tin foil, the circuit is completed through the moistened paper on the cylinder of the receiving instrument and a mark is made on the paper, but when the point of the transmitting instrument is pressing on the varnish writing, the circuit is interrupted and the marking ceases. In this manner, as the corresponding cylinders rotate, spiral lines very close together are drawn by the point of the receiving instrument, excepting in those places where

the electric circuit is interrupted by the varnish, and if both cylinders rotate exactly together the point of the transmitting instrument, by passing several times over different parts of the same letter, will cause the marking point to produce the forms of the letters on the prepared paper. It is essential to the success of the process that the cylinders of the corresponding instruments should move synchronously. To effect this I employ electromagnets to regulate the rotations of the cylinders at certain intervals.

In the mode I prefer of doing this the electro-magnets are brought into action by the intervention of pendulums, which are actuated by clockwork. Each instrument has in connexion with it a pendulum, an electro-magnet, and a separate voltaic battery, which may consist of one or two pairs of plates about six inches square. The wires connected with these batteries are so arranged that the pendulums as they vibrate make and break the electric circuit, and bring the electro-magnets into action once or oftener at each vibration. Having by this means set in action the electro-magnets at equal intervals of time I employ their power as regulators of the continuous movements of the cylinders in the following methods. To the keeper of each electro-magnet an arm or small bent lever is fixed, the end of which nearly touches the outer rim of the cylinder where the keeper is attracted to the magnet, and is lifted from it by a spring when the magnetic action ceases. On to the outer rim of the cylinder there are placed several small projections at exactly equal distances, which projections catch or rub against the end of the lever when it is drawn down by the magnet, but pass freely when it is raised. In working the instruments they are so weighted that the cylinders rotate in a small degree faster than the speed they are to be permitted to attain; by which means the projections on the rim of the cylinder touch the bent lever before the electro-magnetic action ceases, and the movements of each cylinder are regulated to correspond by retarding the motion every time that the pendulums bring the electro-magnets into action. The regulating check should never be so great as to stop the movements of the instrument, to prevent which the ends. of the bent levers or regulating detents should be slightly inclined to the projecting studs.

The arrangement of the magnetic regulators may be

reversed by causing the ends of the levers to be pressed towards the rims of the cylinders by springs and to be drawn back by the electro-magnets, instead of employing the force of the magnets directly as the controlling power. Or the regulation of the instruments may be effected by causing the levers to give accelerating impulses to the projections, on the cylinders, in which case the instruments should be so weighted as to move rather more slowly than the resulting motion required. Another mode of applying the electro-magnetic regulator is to cause either of the corresponding instruments at certain intervals of its revolution to bring into action, at the distant station, an electro-magnet by means of a secondary circuit. The mode of bringing electro-magnets into action by a secondary circuit is more fully explained in the description of that part of my invention which relates to the breaking and renewing of electric circuits, I prefer, however, the plan of regulating with the aid of pendulums, because they act independently and with certainty at any distance. In any of the modes of applying the magnetic regulator above described it might be brought to bear on a wheel either higher up or lower in the train than the cylinder, if found desirable.

As a means of ascertaining whether the distant cylinders are moving synchronously I place a strip of paper or other non-conducting substance, on the cylinder of the transmitting instrument, and if the cylinders be moving accurately a straight and perpendicular line is produced on the receiving cylinder; but if one instrument be moving faster than the other or irregularly, the line will be slanting or irregular. By means of this "guide line" the person in charge of the receiving instrument is enabled to regulate it exactly in accordance with the transmitting instrument by regulating the pendulum and adjusting the weight. To start the instruments at the same instant I adopt the following method:-A small electro-magnet formed by numerous coils of very fine wire is brought into action by the electric current transmitted along the telegraphic wires. To the keeper of this magnet a small bent lever is attached, which bears against the fan of the receiving instrument and keeps it from revolving as long as the magnet is in action, but when the electric circuit is momentarily broken, by the starting of the transmitting instrument, the keeper falls back and

the fan being released, the receiving instrument is set in motion. Instead of employing a piece of soft iron for the keeper of this electro-magnet a small permanent magnet may be used, the poles of which should be so placed that when the electric current passes, the electro-magnet shall repel the permanent one and liberate the fan. This arrangement for starting the instrument is also applicable for sounding an alarum. To copy print with these instruments a portion of the printer's ink may be transferred from the printed paper to tin foil by pressure, or the tin foil may be printed on directly from types. In copying small print or small writing the cylinder of the receiving instrument should be of greater diameter than that of the receiving instrument, and the thread of the screw for the traversing-nut should be coarser in proportion, so as to produce a magnified copy of the original, for greater distinctness.

Another arrangement for copying by means of electricity may be adopted, which consists in the use of several points instead of only one or two, as in the mode before described. When several points are used with only one conducting wire the points are placed close together yet insulated from each other; the range of points being sufficient to cover the depth of one or more lines of writing. Similar ranges of points press on the message to be transmitted and on the paper of the receiving instrument, and the electricity is caused to pass through the points alternately in rapid succession at corresponding points, in such manner that they may transmit the electric current at the same instant. The ends of the wires connected with the points are inlaid in a disc of ivory in a circular form, and are so arranged that wire springs attached to one of the rapid revolving-wheels of the instrument pass over them in succession, and thus transmit the electric current through the wires alternately. The synchronous successive transmissions of electricity through corresponding points are attained as in the preceding arrangements by the regulating power of electro-magnets brought into action at certain intervals. In this plan of copying with several points the rotation of the cylinder must be much slower than that of the screw with the traversingnut, so that the electric current may pass through the range of wires about four times in the formation of each

letter in the series of lines of writing covered by the points.

The accompanying drawings of the arrangement for the copying telegraph from fig. 2 to fig. 4 inclusive, are made to the scale of half an inch to an inch.

Fig. 1, is on the scale of about one inch to one foot. The same letters refer to the same parts in each.

Fig. 1, is a front elevation of the copying telegraph (with a single point) mounted on its case; T, is the frame containing the train of wheels for communicating motion to the cylinder, c, P, is the end of the arm attached to the traversing-nut with the point resting on the cylinder; the arm and screw being hidden from sight by the cylinder. м, is the regulating electro-magnet. L, the bent lever fixed to the keeper, which presses on the projecting-studs on the wheel or disc, R, which is here represented as fixed to the arbour of the cylinder; this plan being more convenient than having the projections placed on the rim of the cylinder, though either mode will answer equally. B, is the pendulum moved by clockwork, which makes and breaks the electric circuit of the voltaic battery, v', to bring into action the magnet, M. The starting magnet, m, is placed near the fan, F. v1, v2, v3, are the voltaic battery and connecting wires for the long circuit; v', v2, v3, v, are the quantity battery and wires connected with the regulating electro-magnet. A, is the supporting case, and w, the weight.

Fig. 2, is a plan of the instrument; D, is a small drum to wind up the weight. The cord passes over a pulley, o, and is not fixed to the drum, but is wound round it a few turns, the cord being kept stretched by a small counterpoise. The object of this arrangement (which is more clearly shown in fig. 6) is to confine the propelling action of the weight to the middle of the drum, but this is not essential to the correct working of the instrument, and an ordinary clock pulley is represented in fig. 1. s, is the screw on which the nut, N, traverses, carrying the arm, H, and the point, P. The thread of the screw must be proportioned to the size of the writing intended to be copied, as it should carry the point at least six or seven times over each letter to bring out the form of the letters distinctly. M, is the regulating magnet; J, the stand to which it is fixed; K, the keeper; L, the bent lever; E, E,