390 



Dr. TV. L. Robb on Oscillati 



lOllS 



different spheres were used in the different experiments. The 

 smaller sphere was suspended from a fine wire .and arranged, 

 as represented in the figure, so that the condenser was receiving 

 a charge only when the spheres were in contact. The con- 

 denser was charged by allowing the smaller sphere to swing 

 against the larger and rebound. The length of time that the 

 condenser was receiving a charge could be varied either by 

 varying the size of the smaller sphere, by varying the number 

 of times the spheres were brought in contact, or by varying 

 the velocity of the smaller sphere at the time of contact. The 

 charge of the condenser was measured by allowing it to dis- 

 charge through a Siemens and Halske high-resistance astatic 

 galvanometer and observing the throw of the needle. 



A few preliminary experiments showed the important part 

 played by the resistance of the charging circuit in determi- 

 ning the charge given to the condenser in any given time. 

 Table I. gives the results obtained with two Latimer- Clark 



Table I. (See 



also diagram 1.) 



Cell No. 489. 



Cell No. 491. 



- 

 Time Condenser 

 was charged. 



X 



Charge, in micro- 

 coulombs. 



Time Condenser 

 was charged. 



Charge, in micro- 

 coulombs. 



1-248 



X 



0215 



2X 



T392 



2X 



0445 



3X 



1-417 



3X 



0-614 



4X 



1-422 



4X 



0-749 



5X 



1-426 



5X 



0-858 



10 X 



1-428 



10 X 



1-187 



20 X 



1-434 



20 X 



1-383 



cells numbers 489 and 49.1, manufactured by Muirhead and 

 Co. The condenser used was a paraffin condenser of one 

 microfarad capacity. 



When the two spheres S x and S 2 were allowed to come in 

 contact only once, the time is denoted by X ; when the con- 

 tact was made twice, by 2X &c. Care was taken to have the 

 velocity of the smaller sphere at the moment of contact as 

 nearly as possible the same in all experiments. This was 

 attained by having the smaller sphere always released at the 



