290 Mr. J. Tykocinski-Tykociner on the 



frequencies, but depend upon the ratio of the frequency 

 of generated oscillations to the number of interruptions per 

 second the buzzer is operating. Those oscillations, the 

 frequencies of which represent exact multiples of the number 

 of buzzer interruptions,, have the largest amplitudes. 



Basing himself on this result, Dr. Mandelstam devised 

 (July 1915) and developed the following method of absolute 

 measurements of frequencies used in radio work. 



A buzzer B (fig. 2) giving regular interruptions and 

 working from a battery of accumulators E excites an 



Fig. 2. 



^£3^ 



* 



aperiodic circuit I consisting of a resistance R and in- 

 ductance L. This circuit is a source of oscillations of: 

 all possible frequencies in accordance with Fourier's 

 analysis of the curve A into sinusoidal components. 

 Another circuit II, capable of performing free oscil- 

 lations, with its variable capacity C 2 and inductance L 2 is 

 inductively connected with the generating circuit I and 

 with, a circuit III, containing an indicating instrument D, 

 as for instance a thermo-element w r ith galvanometer or a 

 detector with a telephone. 



By variation of the capacity of the condenser C 2 a great 

 number of maxima of the oscillating currents in II can 

 be observed, arranged in definite positions all along the 

 scale of the condenser C 2 . Changing the number of 

 interruptions per second of the buzzer produces the effect 

 that the maxima come closer to each other if the number 

 of interruptions decreases, or become widely separated if 

 the number of interruptions increases. The use of a 

 detector with a telephone in the indicating circuit III 

 coupled with If gives a means of hearing a pronounced 

 musical tone, corresponding to the frequency of inter- 

 ruption of the buzzer only in positions of the condenser C 2 

 which form circuits of multiple natural periods to that of 



