- Email: [email protected]
Researches on vagabond currents
Feb., i922.]
CURRENT TOPICS.
28 7
printed. Prof. Nihal Karan Sethi, of the Benares Hindu University, and, jointly, C. V. Raman and K. Seshagiri Rao, and, again jointly, C. V. Raman and Goverdhan Lal Datta, of the University of Calcutta, present papers in the field of optics, while from A. L. Narayan, Maharajah's College, Vizianagaram, Madras, comes a paper " On Sounds of Splashes." There is at least one paper from Wales, and one from Oxf,ord, while Cambridge contributes a larger number. London and Manchester are repre~nted. R . W . Wood, of Johns Hopkins, L. T. More, University of Cincinnati, E. P. Adams, of Princeton, and E. Buckingham, Bureau of Standards, form the contingent from the United States. G. F. S. Researches on V a g a b o n d Currents. J. CIIAPPIUS and HUBERTDESPREZ. (Comptes Rendus, Nov. I4, I92I.)---The currents referred to are such as wander from an electric generator through pipes in the ground and through the earth itself back to the generator, hi a city there is likely to be a group of several such currents superimposed and flowing through the same conductors. A method of determining the sources is much needed. When a vagabond current is made to actuate a telephone receiver a sort of frying sound is heard to which components are contributed by sudden variations in trolley currents, by changes in the speed of dynamos and also by those undulations in the current developed by direct-current dynamos which are due to the impossibility of maintaining the current unchanged from the instant a brush passes over to one segment of the commutator until it makes the next similar change. The experimenters developed a resonance arrangement by which the sound due to the undulations could be isolated from the sound complex and its frequency measured. As the latter depends on the number of revolutions per second made by the armature and on the number of segments on the armature there is something individual and characteristic about it. There might, however, be several dynamos emitting undulations of the same period. H o w shall the very " fons et origo malorum " be selected from several possible contributing dynamos? This was accomplished by connecting a three-electrode vacuum tube to the dynamo circuit in such manner that vibrations caused by the voice or by whistling could be superimposed on the current from the generator. If a stray current was found to give in the telephone receiver these added sounds, its source was at once known beyond question. G. F. S. Sea Casualties and L o s s of L i f e . m A paper on this subject was presented lately before the Northeast Coast Institution of Engineers and Shipbuilders (Newcastle-on-Tyne) by Sir W. S. Abell. The question of safety at sea has been a matter of interest from the earliest times, but it is, perhaps, true that property was at first more
CURRENT TOPICS.
28 7
printed. Prof. Nihal Karan Sethi, of the Benares Hindu University, and, jointly, C. V. Raman and K. Seshagiri Rao, and, again jointly, C. V. Raman and Goverdhan Lal Datta, of the University of Calcutta, present papers in the field of optics, while from A. L. Narayan, Maharajah's College, Vizianagaram, Madras, comes a paper " On Sounds of Splashes." There is at least one paper from Wales, and one from Oxf,ord, while Cambridge contributes a larger number. London and Manchester are repre~nted. R . W . Wood, of Johns Hopkins, L. T. More, University of Cincinnati, E. P. Adams, of Princeton, and E. Buckingham, Bureau of Standards, form the contingent from the United States. G. F. S. Researches on V a g a b o n d Currents. J. CIIAPPIUS and HUBERTDESPREZ. (Comptes Rendus, Nov. I4, I92I.)---The currents referred to are such as wander from an electric generator through pipes in the ground and through the earth itself back to the generator, hi a city there is likely to be a group of several such currents superimposed and flowing through the same conductors. A method of determining the sources is much needed. When a vagabond current is made to actuate a telephone receiver a sort of frying sound is heard to which components are contributed by sudden variations in trolley currents, by changes in the speed of dynamos and also by those undulations in the current developed by direct-current dynamos which are due to the impossibility of maintaining the current unchanged from the instant a brush passes over to one segment of the commutator until it makes the next similar change. The experimenters developed a resonance arrangement by which the sound due to the undulations could be isolated from the sound complex and its frequency measured. As the latter depends on the number of revolutions per second made by the armature and on the number of segments on the armature there is something individual and characteristic about it. There might, however, be several dynamos emitting undulations of the same period. H o w shall the very " fons et origo malorum " be selected from several possible contributing dynamos? This was accomplished by connecting a three-electrode vacuum tube to the dynamo circuit in such manner that vibrations caused by the voice or by whistling could be superimposed on the current from the generator. If a stray current was found to give in the telephone receiver these added sounds, its source was at once known beyond question. G. F. S. Sea Casualties and L o s s of L i f e . m A paper on this subject was presented lately before the Northeast Coast Institution of Engineers and Shipbuilders (Newcastle-on-Tyne) by Sir W. S. Abell. The question of safety at sea has been a matter of interest from the earliest times, but it is, perhaps, true that property was at first more