When the relay is operated it connects a bell between one of the wires of the circuit and earth, while the bell itself is arranged to respond to current pulsations in one direction only.
The great reduction in friction and in electrical resistance of the contact thus effected between the recurved end of the arm and the rotating surface secures the transmission of signals at such a high rate of speed that the combination of this relay with a special form of curb sender allows of the re-transmission of signals into a second cable at a speed not less than that of the siphon recorder worked in the usual way.
The movement of S is obtained by means of a relay engine, in which there are two rams of different diameters; a constant pressure is always acting on the smaller of these when the motor is at work, while the governor (or handpower if desired) admits or exhausts pressurewater from the face of the other, and the movements to and fro thus given to the two rams alter the position of the stud S, and thus change the stroke of the plungers of the main engine.
A key K to one end of the coil of the relay magnet R, II the other end of which is put to earth.
The seeming want of reaction of so much of the cerebellar structure under artificial stimulation, and the complex relay system revealed in the histology of the cerebellum, suggest that the impressions are elaborate.
Owing to the difficulty of maintaining perfect balance on duplexed cables, curb sending is not now used, but the signals are transmitted by means of an apparatus similar to the Wheatstone automatic transmitter used on land lines and differing from the latter only in regard to the alphabet employed; the signals from the transmitter actuate a relay having heavy armatures which in turn transmit the signals to the cable; this arrangement gives very firm signals, a point of great importance for good working.
The synchronous revolutions of the transmitting cylinders are effected by making one cylinder revolve slightly faster than the other; after each revolution the cylinder which is accelerated is arrested for a moment by means of a special relay until the difference of speed is accurately compensated for.
At Kamenka a relay of horses was to wait which would take them to the Warsaw highroad, and from there they would hasten abroad with post horses.
At the receiving station Marconi connected a single voltaic cell B 1 and a sensitive telegraphic relay R in series with his tube of metallic filings C, and interposed certain little coils called choking coils.
The result is that the armature of the relay is attracted, and currents are sent through the sounder from the local battery, producing the signals from the distant station.