IV <Hr 



possible to make th- curve straight ii"r t> nmkf it 

 through the origin. 



If// is the torque required to overcome tin- initial 



n, an initial current / = '71 / will U required to 



' 



start the meter. If /i t and n, are the speeds for cunvnt9 

 c, and f r we shall have, anstiniing the t..n|iie curve to be 

 straight. 



"i _ r .-"V . 



*s <*-</ 



r example, suppose that the curve is straight and 

 inclined to the axis of current or torque at an inclination 

 of T9r\ >. the ratio of any vertical ordinal, in terms of 

 revolutions per minute, to the corresponding horizontal 

 onlinate, measured up to the point where the run.- mt> 

 the current axis, in amperes, is 1*98. Suppose, also, that 

 the starting curn-nt is 0-2 ampere. When the current is 

 3 amperes the speed is 5-.V> r.p.m. ; if the starting cunvnt 

 were nothing it would In* .">'.:. r.p.m., the meter in there- 

 fore running 6*7 per cent too slow. When the current 

 amperes the speed is 2'.' r p.m.. it *hnul<l U> 



p.p. in., the meter is now running 1*3 per cent. 

 alow. Wo see then that t airy inrreaftea with the 



total cun 



Carves for three typeM of cum-nt meter an* givi-n in 



i 7. The cun-eH in the figure give (1) the speed, ami 



rati<> >f the speed to the total current. U.th on a 

 baseoft* 1 :if. In th- Hi.ikhnm tnet4-r the start inc 



current is 0*2 ampere, ami tin- maxiinuin current 2" am- 

 peres. In the Perry meter the starting current i 

 ampere, the maximum current 2o amperen. In the 



