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Voice carried 4900 miles by radio
560
CURRENT ToPIcs.
[J. F. I.
Marine Semi-Diesel Engines. ANON. (The London Times Engineering Supplement, No. 490, August 27, I915.)--So rapid has been the development of the semi-Diesel or hot-bulb motor that it now practically holds the field for all types of motor craft in which the engine installation is anywhere between IOO and 600 horse-power. Below the former figure the paraffin engine is still very largely used, while above 60o horse-power the Diesel engine is better, as a rule, since even this power necessitates a twin-screw arrangement with a hot-bulb installation. The employment of hot-bulb engines for barges and cargo-carrying coastal vessels has long been common, and during the past year it has gained considerable ground in its application to tugs, for which it is eminently adapted. Some such vessels are now to be seen on the Thames, and others have recently been ordered, in the opinion of those who have had most experience in both steam and motor tugs of this type, it is probable that the steam-driven tug will in course of time give way entirely to that equipped with hot-bulb engines, since the economy to be effected by the employment of the cheap heavy oil suitable for hot-bulb motors will render the steam tug in comparison far too expensive to operate. Voice Carried 4900 Miles by Radio. ANON. (ElectricalWorld, vol. 66, No. 15, October 9, I 9 I S . ) - - W i t h a few notable exceptions, radio-telephone workers of the past have been so much given to making extravagant claims for their various instruments, and then failing to accomplish anything even remotely resembling the original promises, that it is gratifying to find a real accomplishment in the art not previously advertised. The human voice was successfully carried across the continent by wireless telephony on September 29 by the American Telephone and Telegraph Company. Speech transmitted from the radio station at Arlington to Mare Island, San Francisco Bay, was also heard clearly at the Pearl Harbor station in Hawaii, 49o0 miles away. It had been known for some time that the American Telephone and Telegraph Company and the Western Electric Company had been experimenting in radio-transmission from the Arlington station of the United States Navy Department, t h e a6rial of which was loaned for that purpose. That the results which would be secured were to be of sv.ch great importance and interest was hardly suspected, however. After a period of preliminary experimentation, in which the special apparatus of the telephone company was connected to the a~rial supported from the three tall towers at Arlington, on August 27 a telephonic test was made from there to Darien, Isthmus of Panama, 21oo miles away. Satisfactory speech was actually transmitted between the naval stations at these points, and greater likelihood of success for the anticipated transcontinental test was thus indicated.
CURRENT ToPIcs.
[J. F. I.
Marine Semi-Diesel Engines. ANON. (The London Times Engineering Supplement, No. 490, August 27, I915.)--So rapid has been the development of the semi-Diesel or hot-bulb motor that it now practically holds the field for all types of motor craft in which the engine installation is anywhere between IOO and 600 horse-power. Below the former figure the paraffin engine is still very largely used, while above 60o horse-power the Diesel engine is better, as a rule, since even this power necessitates a twin-screw arrangement with a hot-bulb installation. The employment of hot-bulb engines for barges and cargo-carrying coastal vessels has long been common, and during the past year it has gained considerable ground in its application to tugs, for which it is eminently adapted. Some such vessels are now to be seen on the Thames, and others have recently been ordered, in the opinion of those who have had most experience in both steam and motor tugs of this type, it is probable that the steam-driven tug will in course of time give way entirely to that equipped with hot-bulb engines, since the economy to be effected by the employment of the cheap heavy oil suitable for hot-bulb motors will render the steam tug in comparison far too expensive to operate. Voice Carried 4900 Miles by Radio. ANON. (ElectricalWorld, vol. 66, No. 15, October 9, I 9 I S . ) - - W i t h a few notable exceptions, radio-telephone workers of the past have been so much given to making extravagant claims for their various instruments, and then failing to accomplish anything even remotely resembling the original promises, that it is gratifying to find a real accomplishment in the art not previously advertised. The human voice was successfully carried across the continent by wireless telephony on September 29 by the American Telephone and Telegraph Company. Speech transmitted from the radio station at Arlington to Mare Island, San Francisco Bay, was also heard clearly at the Pearl Harbor station in Hawaii, 49o0 miles away. It had been known for some time that the American Telephone and Telegraph Company and the Western Electric Company had been experimenting in radio-transmission from the Arlington station of the United States Navy Department, t h e a6rial of which was loaned for that purpose. That the results which would be secured were to be of sv.ch great importance and interest was hardly suspected, however. After a period of preliminary experimentation, in which the special apparatus of the telephone company was connected to the a~rial supported from the three tall towers at Arlington, on August 27 a telephonic test was made from there to Darien, Isthmus of Panama, 21oo miles away. Satisfactory speech was actually transmitted between the naval stations at these points, and greater likelihood of success for the anticipated transcontinental test was thus indicated.