116 PROCEEDINGS OF THE AMERICAN ACADEMY 



The discharge of a glass Leyden jar gave the following values, when 

 reduced to seconds, different lengths of spark being used. 



3.50 



Figure 7 shows that the length of the spark exerts an inapprecia- 

 ble effect. 



The following table gives the values in mill ion ths of a second of the 

 successive oscillations on six negatives taken with small air condenser 

 under the conditions given on the preceding page. The first on the 

 right terminal is a half-oscillation. The rest are double oscillations. 



3.11 3.24 2.90 



3.03 3.03 3.16 



1.74 3.08 3.12 3.22 3.04 3.09 3.07 3.13 3.03 



Left Terminal. 



2.62 3.45 3.25 3.01 2.85 3.22 312 



2.89 3.50 3.08 3.21 



3.11 3.12 3.30 2.96 3.35 3.39 3.16 3.06 



2.75 3.63 3.02 2.97 3.48 3.22 3.00 3.18 3.19 



2.84 3.19 3.-36 2.89 3.41 3.00 



2.88 3.19 3.13 2.90 2.96 



2.85 3.39 3.19 2.99 3.21 3.21 3.09 3.12 3.19 



The values for the different negatives are plotted in Figures 1, 2; 

 the mean value.^?, in Figures 3, 4. The time of the first half-oscilla- 

 tion was doubled in plotting. On each ordinate is plotted the time of 

 one oscillation, — on the first ordinate the time of the first oscillation, 

 on the second the time of the second. It should be noted that the 

 curved lines are meaningless, except where they cross the vertical ordi- 

 nates, serving merely to connect the points belonging to one negative. 



The difference in the time of oscillations cannot be explained by 

 the vibration of the discharging arm lengthening and shortening the 

 sparking distance, .since this would necessitate a vibration frequency 

 of 100,000 per second, and an amplitude of at least one millimeter; a 

 velocity and momentum impossible for the apparatus either to acquire 



