Patterson and Arnold — Electrical Oscillations, etc. 359 



Art. L. — On Increasing the Frequency of Electrical Oscilla- 

 tions ; by A. H. Patterson and C. H. Arnold. 



The experiments of Hertz showed that the sparks from a 

 transformer are complex and that only certain sparks, charac- 

 terized by peculiar light and noise, are capable of awakening 

 resonance in neighboring circuits. In fig. 1, G represents 



a suitable alternator, P the primary, S the secondary of a 

 transformer, B an air gap, C a suitable condenser. Each 

 impulse of the generator & causes a corresponding impulse in 

 the circuit S. If the condenser C is suitably charged, at each 

 impulse of the generator sparks will oscillate across the air- 

 gap, B. The time of oscillation of one kiud of sparks will be 

 dependent upon the capacity and self induction in the circuit 

 d, a, b, c, while the time of oscillation of another species of 

 sparks will depend upon the self induction A and S and the 

 capacity C. In general the transformer S serves as a choking 

 coil, and the time of oscillations of the spark at B can be ob- 

 tained from the expression t = Stta/LC, given by Lord Kelvin 

 in a paper on the theory of transient currents, a paper in which, 

 as it has been well said, Lord Kelvin has packed the whole 

 theory of transient currents. 



It is evident, therefore, that only those sparks which occur in 

 a circuit of definite self induction and capacity can awaken 

 sparks in a circuit of equal self induction and capacity. Hertz's 

 work has seemed to illustrate the laws which Lord Kelvin and 

 Maxwell have deduced from theory, and the commercial uses 

 of alternating dynamo machines have enabled recent experi- 

 menters to show many well known phenomena on a much 

 larger scale than was possible when the old form of transformer 

 known as the Kuhmkorf coil was excited merely by batteries. 

 There is danger, however, that in the successful attempts to 

 increase the scale of representation of the remarkable efforts 

 obtained by Professor Crookes the distinction between impulse 

 and oscillation may become obscured. 



An impulse is a sudden throb of a current which is^pro- 

 duced by a change in electromotive force. A generator, for 

 instance, giving 400 alternations of current per second will 



Ah. Jour. Scl— Third Series, Vol. XLYI, No. 275. — Nov., 1893. 

 . 25 



