TELAUTOGRAPH, an instrument for the instantaneous transmission of a facsimile copy of writing or pen drawing. Telautograph was the name given by Elisha Gray, who invented the apparatus to his particular form, but it has been extended to cover varieties of ma chines having the same purpose. In Gray's ap paratus the transmitting pen is connected by silk cords to mechanism by means of which the motions of the pen cause a pulsatory cur rent to pass into two telegraph wires. These pulsatory currents produce rapid pulsatory mo tion of the armature of a system of electro magnets by means of which the receiving pen is caused to follow the motions of the trans mitter. Another electromagnetic arrangement lifts the receiving pen off of the paper at the end of each line, while still another moves the paper forward to receive the next line from the pen. As commonly used a pencil is employed instead of a pen for transmitting and a con tinuous roll of paper is provided at both the transmitter and receiver. The writer or sender of the message pulls a little lever to shift his paper and the motion is conveyed electrically to the paper roll at the receiver. The receiving pen is a capillary glass tube at the junction of two light metal arms. This glass fountain pen cil repeats automatically all the movements of the sending pencil, so that either words, pic tures or signs are accurately duplicated. This apparatus can be used on the same wires as a telephone without disturbing the use of the latter, does not require an operator at the re ceiving• end, and interception of the message by wire tapping is impossible.
In a modified form of telautograph known as the telechirograph, invented by Gruhn, a rad ically different receiving apparatus is used. The transmitted currents influence two electromag nets which in turn cause a small concave mirror to move; a light ray from a small incandescent lamp fails upon the mirror whence it is re flected to a sheet of sensitized paper. The mir ror is attached by means of cement to a small iron plate in the form of a triangle, one corner of which rests upon a set screw upon which the mirror can oscillate. Beneath the two other corners extend two armatures subjected to the attraction of the electro-magnets. These arma tures undergo' oscillations corresponding to the component movements of the transmitting pen cif; they are carried by flat springs, and the os cillations are given to the iron plate and, of course, to the mirror fastened to it. Before the message can be delivered the receiving sheet must be developed; the apparatus for this is simple: when the message is completed a small electric motor operated by an independent bat tery in the receiving room is set in motion; this motor works a train of wheels or rollers which draw the portion of the film written upon by the light • ray through a developing bath and out again through a pair of rubber drying rolls. The completed message is delivered in less than 35 seconds after the transmitting operator has placed his pencil in its rest.