406 



RECENT PROGRESS IN PHYSICS 



Distance of plates. 



Possible increase of electric density on 

 collector 



2 lines. 



9.50 



10. 



3.67 2.21 



20. 



1.45 



30. 



1.25 



50. 

 1.09 



CO 



This is tlie correct representation of the mode of action of the con- 

 densing apparatus. Correct views on the subject had long been held, 

 but not so decidedly and clearly expressed. 



In these experiments, C was connected with B by a wire 8 inches 

 5 lines in length. When a wire 18 inches 3 lines long was used instead, 

 almost exactly the same relative numbers of the striking distance were 

 obtained for the collector standing alone and in the presence of the 

 condenser. 



Consequently, when the conducting system of the collector is brought 

 into contact with a constant source of electricity, there will be accu- 

 mulated on the collector B, 2.21, 1.45, 1.25, &c., times more electricity 

 when the condenser A connected with the ground, is 10, 20, 30, &c., 

 lines distant from B, than if it were removed. 



Biess made direct experiments to determine the increase of the 

 quantity of electricity on the collector by the approach of the con- 

 denser under the above circumstances ; that is, when the collector, 

 during the proximity of the condenser, remained in communication 

 with a constant source of electricity ; the form of experiment was as 

 follows. 



First the ball C was touched with the knob of a Leyden jar, while 

 the condenser was away ; the jar was then removed, and the striking 

 distance at C measured. 



Next, the condenser communicating with the ground was placed at 

 a given distance, C was brought into contact with the knob of the 

 Leyden jar, the condenser jar removed, and the striking distance 

 at C again measured. 



The striking distance was found to be in the last case as many times 

 greater than in the first as the electricity imparted to the plate B in the 

 last instance was more than in th.e first. 



A series of experiments gave as a mean the following quantities of 

 electricity for the different distances of the plates : 



Distance of plates 

 Electricity obtained 



The difference between these observed numbers and the densities 

 computed from the first experiments is really very small. 



For distances less than 10 lines reliable experiments could not be 

 made. 



The proportion of the quantity of electricity on the collector, accord- 

 ing as it stands alone during contact, or near the condenser, is called 

 the coefficient of accumulation of the condenser. According to the 

 above experiments, therefore, the coefficient of accumulation of the 

 condenser is 2.21, 1.45, &c., when the plates are 10 lines, 20, &c., 

 apart. 



