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Franklin Times, Volume 10, Issue 798, 9 January 1923, Page 4

■The phrase “listening in” is now becoming familiar in connection with broadcasting (says the Otago Daily. Times). It has ,however, other possible applications. Experiments have for example, been carried out in the use of public electric, supply circuits both as antennae for wireless receiving and also as paths along which electric waves can be transmitted to special receivers connected to lampholders. In this exepriment it was found that there was a good deal of interference, caused by the switching;, on and off of motors and by other occurences in connection with the ordinary use of electricity supply. A. British inventor has happy thought of adapting a f receiving device to the actual observiiigr of theso j disturbances. For example, by “lis- i tening in” on any part an electric supply system it is pp(ssible to detect when an »Eiotor is working badly. A motor which is running well has a particular note, ;and one running badly is distinguished by its peculiar noise, which can heard above the others. Etven the®| slipping of a belt can be detectedThis ingenious device has been actually employed in keeping watch upon a pump motor which was at woi’k continuously at a remote point. The least irregularity in the working of this pump could be easily be heard by “listening in,” and therefore the engineer in charge could tell whether it was necessary to send a man to adjust the machine.