A TELEGRAPHIC DISCOVERY.

The development of the phono- i pore, which comprises a system of t multiplex telegraphy, has been < watched by electricians with great ' interest. The phonopore is the in- ] vention of Mr. Langdon-Davies, and , his system of telegraphy may be de- i scribed generally as the application ' to an ordinary telegraph line of cer- j tain instruments and apparatus which ■ first give to a current of electricity an i extremely rapid vibratory character < — that is, send into a telegraph line 1 a succession of electrical impulses so \ short, and with such great rapidity, that ordinary telegraph instruments ! are in no way affected by them — and ■ then, by means of other apparatus ' forming part of the system, enable j such pulsatory current to work relays | and other telegraphic instruments. < And this system is carried out without ' affecting, or being affected by, the \ ordinary telegraphic signals, which , may be transmitted through the same < conductor at the same time. Messages may be simultaneously trans- ■ mitted from opposite ends of the ■ same wire through which the 1 ordinary telegraph service is being i worked, thus trebling the working ' capacity of any line to which it is ap- \ plied. The inventor has also per- 1 fected an arrangement for the j application of the phonopore to telephonic purposes. By meanß of the phonopore, telephonic communi- -, cation can be carried through an , ordinary telegraph wire without i interfering at all with the telegraph- < ing. On the Great Western Railway two signal boxes, three and a half < miles apart, hare been telephonically

connected by means of this invention, the telephone being installed on a block signalling wire — a wire which everywhere is sacred to block signalling alone, as the safety of trains and passengers depends on the comt munication being kept free from all interruption. The system is found, to answer admirably, the two services , on the same wire in no way inter- > fering with each other.