6S2 Prof. Fleming and Mr. Richardson on the Effect of an 



if the frequency of resonance is N and the corresponding 

 inductance of the cymometer is L, we should have 



as a check on the observations. 



The following details of one set of experiments will show 

 the advantage gained by the use of the blower. The experi- 

 ments were made with cymometer No. 2. The primary 

 circuit had an inductance of 5012 cms. and a capacity of 

 0*002645 mfd., and was charged by a 10 in. induction-coil 

 worked with a coal-gas mercury turbine break. The spark- 

 balls were brass balls 3 cms. in diameter set with spark-gaps 

 of length of 1, 2, and 3 mm. respectively in various experi- 

 ments. The resistance added in the cymometer circuit was 

 a very fine constantan wire of which the resistance was 

 7*1 ohms, and a similar wire against which a thermoj unction 

 pressed has a resistance of 5*0 ohms. 



When the cymometer circuit was adjusted to be in 

 resonance with the primary circuit the resonance frequency 

 N was found to be 1*25 x 10 6 and the corresponding induc- 

 tance of the cymometer was 5500 cms. Hence for the added 

 resistance, we have R = 7 # lx 10 9 C.G.S., L = 5500 cms., and 

 n= 1*25 x 10 6 . Therefore 



= 0-0258, 



JL. 



7-1: 



xlO 9 





4nL ~ 



"4xT25x 



10 6 x 



5500 



and for the thermoj unction 







H 



5x 



:10 9 





4ti%L 



4xl*25x 



10 6 x 



5500 



= 0-0181. 



The thermojunction ammeter having been calibrated with 

 direct currents so that from the deflexions of the Paul single 

 pivot galvanometer the P.M.S. value of the oscillations 

 passing through the wire which gave any observed deflexion 

 could be obtained, a series of observations was taken by 

 varying the setting of the cymometer slowly and continuously 

 when it was placed in loose inductive coupling with the 

 primary circuit so as to alter its oscillation constant 0= VGL, 

 or the product of its inductance L and capacity C_, from which 

 the natural frequency n of the circuit is at once obtained by 

 the formula n = 1/2 ir \/CL. At the same time the R.M.S. 

 value of the current a in the cymometer was read off by the 

 thermo-ammeter and the maximum value A also taken and 

 the resonance frequency N. These observations then give the 



