108 Mr. J. E. Moore on a Continuous and 



London 'Electrician'' of Feb. 3, 1893, and also in the New 

 York 'Electrical World' of Feb. 4, 1893, and need not be 

 entered into here. 



Although the alternating-current magnetometer can plainly 

 be used equally well for continuous and alternating currents 

 of any frequency, yet as a method of measuring losses in iron 

 under widely varying conditions of magnetization and pe- 

 riodicity it necessitates the separate observation of a compa- 

 ratively large number of quantities, the subsequent calibration 

 of these quantities, and finally the graphical representation of 

 them, before the desired estimation of losses can be made. 



§ 3. It seemed desirable, therefore, in order to facilitate the 

 investigation of the nature and amount of the losses in iron, 

 carried through magnetic cycles varying widely in both am- 

 plitude and in time, to devise an instrument that would, first, 

 be independent in its action of the time required to complete 

 the magnetic cycles ; second, be accurate and reliable, and 

 give indications capable of interpretation in Absolute Units ; 

 third, that would reduce the number of observations required 

 to obtain the losses to an absolute minimum ; fourth, that 

 would read directly the quantities to be measured ; and fifth, 

 that would allow measurements to be made in the least pos- 

 sible time. 



It is attempted to fulfil these conditions in the present 

 instrument in the following way : — A system of two small 

 helices is so suspended and mechanically connected that any 

 angular displacement about a vertical axis, given the one, is 

 imparted to the other also, while one of the two helices 

 may receive independent angular displacements about a hori- 

 zontal axis besides. The arrangement and connexions of the 

 magnetometer system will be immediately seen from the 

 accompanying diagram (fig. 1). If the losses in iron mag- 

 netized by an alternating current are to be measured, an 

 intermittent current of the proper periodic time (secured, as 

 previously indicated, by a revolving contact-maker on the shaft 

 of the alternating-current generator) is passed through the 

 helices of the suspended magnetometer system in series, 

 making of the small helices during the very short time the 

 current is flowing in them virtual magnets. If now the 

 sample to be tested, in the form of a long rod supplied with 

 the proper magnetizing coil, be adjusted so that its axis is 

 vertical and lies in the vertical axis of suspension of the 

 magnetometer system, and it be magnetized by an alternating 

 current from the generator whose armature- shaft carries the 

 revolving contact-maker, only that one of the magnetometer 

 helices which is capable of displacement about a horizontal 



