THE system of wireless telephony upon which Capt. Cohn and Lieut. Jeance, of the French Navy, have been at work for some years has recently been considerably improved, and some very successful experiments were carried out last June, when, during some tests in which long-distance communication was established in France by means of an aerial only 164 ft. high, speech was incidentally overheard on a small amateur installation in Lincolnshire. The continuous. waves used for transmission are produced by three arcs connected in series. Each has a negative electrode or carbon only r mm. diameter, and a copper disc negative electrode above it, which forms part of the bottom of a cylindrical tank filled with paraffin and cooled by water circulation. The carbon electrodes are beneath this disc, and their height is regulated by means of a crank outside the arc chamber. The arcs, which are very short, burn in an atmosphere produced by mixing acetylene and hydrogen generated from calcium carbide and calcium hydride respectively, and this not only prevents the burning away of the carbons,. hut actually increases their length slightly during operation.