This telegraph is now in successful operation at No. 10 Wall street, where we had an opportunity of witnessing the simultaneous sending and receiving of a message to and from Philadelphia, one day last week. It is operated by keys, and prints despatches in Roman characters from a revolving type wheel, like the House telegraph. The two messages referred to were sent on a onerwire line—the one from New York passed on the wire, the return message on the ground part of the circuit. It is more simple than the House telegraph, but far more complex than the Morse telegraph—the latter is our favorite on account of its simplicity.