Discussion on “a tubular electrodynamometer for heavy currents“ (Agnew), “measurement of alternating current of low value” (Newman): “to measure an alternating-current resistance and compare it with the direct-current re

W. H. Pratt: Dr. Agnew´s paper tells about the usual procedures in making a wattmeter for high current measurements, by stranding the conductor. Now, stranding the conductor must necssarily be done in a very careful manner, otherwise troubles will be encountered, but it performs two functions; it prevents the formation of eddy currents due to the field of the current coil itself, and it also prevents the formation of eddy currents due to induction from the moving coil. In an instrument in which you are going to get the highest possible sensibility it would seem that this should be taken account of. I see no reference to this in the paper.