658 



Mr. C. G. Barkla on the Velocity of 



From this the positions of the bridge dividing the circuits 

 in the other simple ratios given below were calculated. 



The positions of the bridge giving the five principal maxima 

 as shown on fig. 3 were approximately determined. 



In this experiment the distance from A to the mid point of 

 KK' was 750 - 3 cm., the length of BIT 8 cm., and the equiva- 

 lent length of AS (including the capacity) 158*9 cm. 



Ratio of equiva- 

 lent lengths of 

 circuits. 



1:4 

 1:2 

 3:4 

 3:2 

 5:2 



Table II. 



Calculated 



distance of 



bridge from A. 



20*5 cms. 

 141-5 „ 

 230*2 „ 

 387-4 „ 

 492*2 „ 



Distance of bridge 

 from A, experi- 

 mentally determined. 



23*5 cms. 

 141-5 „ 

 226-0 „ 

 388*5 „ 

 491*3 „ 



More careful determinations were made with a system of 

 different dimensions. The distance from A to the mid point 

 of KK' was 806*5 cm., the length of the movable bridge 

 29 cm., and the equivalent length of the portion AS was 

 taken as 143 cm. The agreement in this case was very close, 

 though shorter bridges give better definition of the maxima. 







Table III. 





Eatio of equiva- 

 lent lengths of 

 circuits. 



Calculated 



distance of 



bridge from A. 



Distance of bridge 

 from A, experi- 

 mentally determined 



1:4 





38*2 



cms. 



38*4 cms. 



1:2 





168*65 



55 



168*65 „ 



3:4 





261-9 



;? 



260*0 „ 



3:2 





429-6 



V 



430-2 „ 



5:2 





541-4 



55 



537-3 „ 



The other positions of the bridge giving maxima of de- 

 magnetization could not be experimentally determined with 

 such accuracy as that in w 7 hich the circuits were divided in 

 the simple ratio 1:2. 



It was also found, as might be expected, that a shorter 

 bridge gave more cusp-like and better defined maxima. 



In Rubens's experiments, in which KBB'K' was an open 

 circuit, the maxima were given for positions of the bridge 



