INTRODUCTORY 5 



in modifying tln-ir <1< ifl regards tlie proportions of the 



i. tic and copper circuits. At that time we meas . 

 core losses hy dynamometer-wattmeters of the Siemens 

 IIM 'oiiMstencies in the measurements compelled us to 

 turn our attention to the study of errors in wattmeters, and 

 led to realise tin- importance of "swamping" the 

 inductance of the pressure coil hy the use of very hiu'h n 



<und non-inductively. in series with the pressure coil. 



-, of course, involved weaker forces and tin- use of weaker 



torsion spring. 'I' lie friction of the contacts dipping in the 



ury cups constituted an annoying source of error. We 



d d tliroiiL'h these ditliculties to no inconsiderable 



nt l.y the inspiring co-operation of Mr. Ernst I >anielson, 



\\-ho had then (1891 and 1892) joined the company hy whom 



IS emph'V i. hanirl.so: .ra.^'d me to study I >r. 



rnatf-cu: 



I niing, for the actual cases 

 of c "iir firm's trail-formers. 



Ions in! -formers Of Other firms \\hieh 



i ..iir hand-, I wi-11 rt-mrmher a Swinhimic hedge- 



isformer. A certain transform. -r from another lirm, 



inti-ivstrd me dr.ply at tli- time. , r Jiad fully 



as much iron and t\\ir, a- much co;.p-r a- tl 



h the material of the oore was of excellent 



magnetic quality, this lavish expenditure loi --rial 



been so ill-utilisrd tl the core 1 the 



regulation of this ti ier were mucli \\oi>e th 



usual | Such i 



: lessons for engineers. 



the!l 11; I still 



imp ance was 



brought about as follows: It had to he th. custom 



Mg department to make its <>\\n 



core-loss tests, merely hiinu'iiiL' amometera to the 



iiment room in we shou ate them at 



