CHAFFEE. — IMPACT EXCITATION OF ELECTRIC OSCILLATIONS. 311 



The following table and the curves of Figure 19 give an idea of the 

 result of increasing the number of gaps in series. The values of the 

 efficiency and power may be somewhat misleading as the adjustments 

 were not for conditions of maximum power and efficiency. The general 

 shape of the curves, however, may prove of interest : 



As was stated in Part I, a proper choice of dynamo permits the 

 omission of the external resistance. The dynamo, for use in this 

 manner must be characterized by a rapidly falling voltage-current 

 curve in order that the voltage will increase if the discharge tends to 

 stop. The high voltage on' open circuit of a generator of this kind also 

 serves automatically to start the gap or gaps. 



(2) Applications. 



Various applications of the continuous oscillations might well be 

 spoken of, but reference will be made to only three, i. e. : the use of the 

 oscillation system in conjunction with a Braun tube for demonstration ; 

 the calibration of a wave meter by means of harmonics ; and wireless 

 telegraphy and telephony. 



The simplicity and convenience of the system as a generator of con- 

 tinuous high frequency oscillations render the apparatus particularly 

 suitable for demonstration and laboratory use. Especially is the sys- 

 tem of value when used in connection with a Braun tube, for, with such 

 an equipment, many of the phenomena of electrical oscillations can be 

 visualized, such as the damping due to resistance, the damping due to 

 radiation in an antenna, etc. 



As was pointed out in Part II, two secondary circuits of different 

 periods can be caused to oscillate, the exact ratio of frequencies being 

 given directly by the resulting Lissajou's figure. If, then, the period 

 of one of the secondary circuits is fixed and accurately determined in 

 some manner, the period of the second variable secondary circuit is 

 given in terms of the first or standard. In this way, with proper ad- 

 justments, a large number of determined periods can be obtained, and 

 an accurate calibration of a wave meter made.*^ 



** Suggested by Professor G. W. Pierce. 



