Oscillatory Discharges. 19 



whereas with those performed with the bridge it lasted only 

 about -J- o£ a sec. 



With the latter ones a greater approximation to the con- 

 ditions o£ action o£ the condenser during the measurements 

 of the period of oscillation is thus secured. 



We will therefore presume that the value most suitable 

 for our calculations is the one derived from our absolute 

 determinations, i. e. Capacity. 



[c.g-.s.] Microf. 



For condenser No. 1 7178 0-007976 



No. 2 7096 0-007885 



For both condensers in 



parallel 14175 0'01575 



For both condensers in 



series 3568 0'003965 



18. To these values for the capacity of the condenser there 

 are to be added those of the capacity of the remaining 

 portions of the circuit ; but within the limits of accuracy of 

 our determinations in most cases this additional amount may 

 simply be neglected. 



The case, in fact, where in our experiments this supple- 

 mentary capacity had its maximum value, was the one of 

 the discharge-circuit being made up of a wire 1594 cm. in 

 length, 0*08 cm. in diameter, and arranged in the form of a 

 square at 85 cm. from the walls of the room where experiments 

 were made. 



The capacity of this wire, as calculated in electrostatic 

 measure bv the formula 



z loo- — 



& r 





(r being the radius of the wire, I its length, and d its distance 

 from the walls) was found to be equal to 97 cm. In this 

 case we took this correction into account, whereas in all other 

 cases it was found to be quite negligible as compared with 

 the capacity of the condenser, which for no experimental 

 arrangement was below 3568 cm. 



I). Resistance of Metallic Circuit and of Spark. 



a. Principle of Method. 



19. With these first researches the value of the resistance 



of the circuits used by us was negligible in calculating fche 



period of oscillation by Thomson's formula. But on the 



other hand, the knowledge of the true value o( the resistance 



C z 



