Electrical World, September 5, 1914, page 487:
A radio-telephone set which is designed for an oversea working range of 50 km (31 miles) between ship aerials 100 ft. high and having 200-ft. spans is being placed on the market by the Marconi Wireless Telegraph Company, Woolworth Building, New York.
The set comprises a transmitter and receiver, overall dimensions 22 in. by 18 in. by 17 in. and weight 59 lb.; five cases of dry batteries, over-all dimensions of each case 21 in. by 18 in. by 5.5 in. and weight 70 lb.; one 6-volt, 80-amp-hour storage battery, weight 38 lb.; one switchboard, over-all dimensions 10 in. by 10 in. by 3 in. and weight 5.5 lb., and one receiving battery, over-all dimensions 9.5 in. by 17 in. by 5 in. and weight 20 lb. The set is also equipped with the following accessories and spare parts: two microphone cases and six spare microphone cells, six transmitting valves (double filaments), six receiving valves, one induction coil, one aerial tuning inductance, high-resistance telephones, one set of six crystals set in cups, connecting plugs and leads, six tuning lamps and small dry batteries for microphone and crystals.
The transmitter consists of a specially constructed valve shunted with condensers and induction coils in such a way that a continuous stream of oscillations is produced. The frequency of these oscillations is controlled by means of variable ebonite condensers. The oscillations are induced into the aerial wire through a variable coupling, any tuning required being effected by means of the tuning lamp provided. A simple switch is used to change from talking to listening. This switch can be controlled from a distance in case the microphone is not near the set. A low-voltage current is used to heat the filaments of the valves, and for this purpose an 80-amp-hour accumulator is provided.