Atria prina Nur TELEGRAPHS.— Th e Gray apparatus, invented by Prof. Mishit Gray, of Chicago, consists primarily of two instruments, a receiver and transmit ter, each provided with a pen. The transmitting pen is connected to operate circuit making and breaking devices, termed " interrupters." located in two electric circuits and arranged to interrupt the currents passing over the respective circuits at short intervals, producing current pulsations as the pen is unwell in two directions crosswise of each other in forming characters, the number of pulsations in the respective circuits being determined by the dis tance which the pen is moved in the respective directions. These two circuits pass through the receiver and include two pairs of " receiving magnets," the armatures of which act to impart a step-by-step movement to the receiving pen in two directions crosswise of each other, the number of steps in each direction being determined by the number of times the respective circuits are interrupted. By this means the movements of the transmitting pen in the two directions operate through the interruptions in the currents passing over the cir cuits to impart corresponding movements to the receiving pen, and thus reproduce the matter written by the operator.
The accompanying illustrations, Figs. 20 and 21, show respectively a general plan of the transmitter and receiver. The transmitting pen, A, is connected at its point to two cords or other flexible connections, F (4, which extend horizontally at right angles to each other, and operate the two circuit making and breaking devices, R (7, termed the " interrupters," located in the two main circuits, connected to 1? and C. The arrangement is such that as the pen. _1, is moved from left to right and rice versa, the circuit of B is made and broken repeatedly in quick succession, producing pulsations therein, varying in number with the linear extent of the movement of the pen, and varying in speed of succession with the rapidity of such movement : while, as the pen is moved up and down in forming the charac ters, the circuit of Cis interrupted and pulsations produced therein in the same manlier.
The two interrupters, B C, are exactly similar in construction. Each of the cords, FO, is wound upon a small drum upon a shaft to which one wire of the circuit is connected. The shaft is provided with an arm, the end of which carries a brush which sweeps in contact with the face of a metallic disk, to which the other wire of the circuit is connected. The face of the disk over which the brush sweeps is provided with insulating strips, so that as the brush sweeps over the face of the disk in either direction the current passing over the circuit in which the brush and disk are located will be made and broken repeatedly in quick sue cession, Each of the shafts is also provided with a second cord, which is wound upon the shaft in the direction the reverse of the cords, G, and is connected to a spring which keeps the cords, F and G, taut at all times. Each of the cords passes between guides located
between the pen and the shafts, and the cords are provided with stops which engage with the guides and arrest the cords and limit the movement given to the shafts and brushes.
The transmitting instrument is also provided with two local circuits, which include local batteries and a pair of pole changers, D E, which are located, respectively, in the main cir cuits of 13 and C, and which act to automatically change the polarity of the currents passing over the respective circuits whenever the movement of the transmitting pen in either direc tion is reversed.
The pole changers, D E, are connected to the two poles of the main batteries, and to the two wires of the respective main circuits, in the usual manner. For the purpose of operating the pole-changers, the cords, le C, pass around pulleys, P P, mounted upon shafts, which operate circuit makers and breakers. included in the respective local circuits. For this pur pose the shafts are provided with arms, which are frictionally connected to the shafts, and hare a limited inurement between fixed stops. The arms, and one of the stops of each arm, are included in the respective local circuits, so that the rocking of the arms between their stops operates to make and break the local circuits, and thus operate the pole changers, D B, to change the polarity of the currents passing over the main circuits of Band Cat each vibra tion of the arms.
It will now be readily understood that, as the pen makes the down strokes in forming the characters, the cord, F, will be unwound from the shaft of the interrupter, V, revolving the shaft, and moving the brush over the disk, and interrupting the current over that circuit repeatedly and in quick succession, the number and rapidity of the interruptions being deter mined by the speed and extent of the movement of the pen.
As the pen makes the upstrokes, the spring will rewind the cord, F, and move the brush in the reverse direction, interrupting the current in the same manner. It will also be under stood that, as the pen moves upward, the cord, passing around the pulley, P, will close the local circuit of the pole changer, E, and send currents of one polarity over the line to C; and, as the pen moves downward, the pulley will open the circuit of the same pole changer, so as to send currents of opposite polarity over the same line.