The transmitter, as above described, is in the square box, and its round black diaphragm may be seen behind the round hole into which one talks. [Footnote: Shouting into a telephone doubtless comes of the idea, unconscious, that one is speaking to a person at a distance. To speak distinctly is better, and in an ordinary tone.] The receiver is the trumpet-shaped tube which hangs on its side, and is taken from its hook to be used. The call-bell has nothing to do with the telephone. It is operated by a small magneto-generator,--a very near relative of the dynamo-the current from which is sent over the telephone circuit (the same wires) when the small crank is turned. Sometimes the question occurs: "Why ring one's own bell when one desires to ring only that at the central office?" The answer is that both bells are in the same circuit. If the circuit is uninterrupted your bell will ring when you ring the other, and a bell at each end of your circuit is necessary in any case, else you could not yourself be called. When the receiving instrument is on its hook its weight depresses the lever slightly. This slight movement _connects_ the bell circuit and _disconnects_ the telephone circuit. Take it off the hook and the reverse is effected. The long-distance telephone differs from the ordinary only in larger conductors, improved instruments, and a metallic circuit--two wires instead of the ordinary single wire and ground connections. [Illustration: TELEAUTOGRAPH TRANSMITTING INSTRUMENT.]