45 



90 





Fig-. 3. 



r ^"^W 



Angle of Phase. \ 



/ 's 

 / // 

 1 if 



/ // 



1 / / 



135 



180 225J 



276 315 SOtf 







50 

 40 



XD 



30 k 



20 



10 



The ordinates of the firm line marked ll Light Curve " represent the peri- 

 odic variation of illuminating-power of the centre of the true arc of an 

 alternating-current arc. The other curves marked E.M.F., Current, and 

 Power represent the variation of potential difference of the carbons, 

 current, and power in the arc. Carbons, 15 mm. cored ; — = 83-3 ; 

 amperes = 14; volts =39; length of arc, 0*55 cm.; volts at alternator 

 terminals=104. (See Table I. A.) 







Fig. 4. — Intensity of Light from Crater. 





25 



- 



/ v « 



/ % 





r^^T^ 



20 



r\ 



/ -*- \<^ 





2^Tv- 





\ \ 





/ //' 



7 > 



\ 



rt 15 



!- 



v\\\ 



. f Carbon 'Positive \ 



/ .'/'' 



*\ 



a. 





// W N 



Lj/i' 





g 10 

 < 



m 'J » o y 



~T \^ / 



if/ 

 / / Carbon 



5 



/ "\% /• // 



,gative 







/ Angle of Phase % \f /// 



/ 









L\ SO ' 180 // 



270 









\ \ <*'/ 







i 





\ \ T.me ^/7 











\ " Mi -^ **/ / 









\ \ ») > ,*>/*/■ 







\ *\ * / *7 











\ • .*v */ 











\\ / U// 



\*S. / / 







Frequency =83-3 ~. Length of arc=0-42 cm. (See Table I. B.) 



