Electrical Oscillations in Air. 329 



that a simple cross-hair, unaided by a lens, moving directly 

 against the negative, was better than any eyepiece. Measure- 

 ments were made of the intervals between the electrical oscil- 

 lations at both terminals. 



In later experiments a smaller air condenser was employed, 

 for reasons which will appear in the conclusions of our paper. 

 A summary of the details and dimensions employed is given 

 herewith. 



Small air-condenser (No. 2), cylindrical. 

 19 zinc cylinders. 

 Height 30*47 centim. 

 Diameter of inner cylinder 7*60 centim. 

 Diameter of outer cylinder 25*95 centim. 

 Average distance apart *5 centim. 

 Capacity (geometric) 5317*9 absolute units — corrected 



for the capacity of ends. 

 Capacity of wire, 200. 

 Self-induction in three sections, radius '0501. 



1. Length, 1197. 



Distance apart of parallel wires, 31*55. 



2. Length, 281. 

 Distance apart, 16*10. 



3. Length, 103. 

 Distance apart, 11*3. 



For alternations of slow period. 

 Ohmic resistance, *742. 

 Self-induction, 41090. 



Theoretical time with these values, '00000310 sec. 

 For alterations of period, '00000310 sec. 

 Ohmic resistance, 1*54. 

 Self-induction, 39700. 

 Theoretical time, -00000304. 

 Distance from spark to concave mirror, 230 centim. 

 Distance from rotating mirror to negative, 259*7 centim. 

 Sparking distance, *23 centim. 



The following is a sample record (see figs. 5 and 6, p. 332). 

 Each negative was measured three or more times, and the 

 mean taken. The lengths are given in centimetres. The last 

 line is the time in miliionths of a second. 









Rig 



ht Terminal. 









•289 



•541 



•561 



•598 



•552 



•511 



•544 



•560 





•295 



•528 



•560 



•595 



•542 



•542 



•550 



•585 



•492 



•290 



•528 



•582 



•602 



■518 



•538 



•550 



•570 



•532 



•292 



•518 



•585 



•592 



•540 











•291 



•529 



•572 



•597 



•540 



•528 



•549 



•572 



•512 



1-65 3U0 3-24 3-38 3-06 3'00 3-11 3"24 2-90 



