CHAFFEE. — IMPACT EXCITATION OF ELECTRIC OSCILLATIONS. 269 



generators. Loosely coupled to this primary circuit is a secondary 

 circuit in which are induced the Wien oscillations. At each breaking- 

 down of the gap a highly damped train of oscillations ensues, which 

 produces in the secondary circuit the two ordinary coupling waves. 

 During the interval between the ending of one primary train and the 

 beginning of the next the secondary circuit oscillates in its own free 

 period. Thus there are produced oscillations of three periods, the 

 latter being of the most importance. 



All of the above mentioned methods for producing oscillations were 

 tried without success by the author in an attempt to obtain oscillations 

 of a frequency of more than 10^ vibrations per second, and of sufficient 

 regularity, continuity, and intensity for use in another investigation. 

 After the failure of the then known methods, further experimentation 

 produced the new oscillation gap and method which are to be studied 

 in the following contribution. The method in some particulars closely 

 resembles the Poulsen method, but in electrical action the system is 

 quite different from any included in the three classes mentioned above. 



The oscillations of this new system do not fall in any of the three 

 classes of oscillations mentioned, but are, as will appear later, inter- 

 mediate between the Poulsen and Wien types. The oscillations pro- 

 duced are unlike the Poulsen oscillations in that their period is but 

 very slightly affected by changes of supply current and not at all by 

 changes of arc length, and they are sinusoidal in wave form. The 

 oscillations are different from the Wien type in being continuous, and 

 having but one period, which is practically the free period of the 

 circuit in which the oscillations are induced. 



It is shown in the following article that this new system produces 

 oscillations superior to the other systems in regularity, which, with its 

 simplicity, commends its use in the laboratory and in practice. It is 

 the only method known by the author for producing intense con- 

 tinuous oscillations at extremely high fr-equencies. The author has 

 obtained continuous and practically undamped oscillations of several 

 amperes at 20 meters wave length, which corresponds to a frequency of 

 1.5 X 10'' oscillations per second. 



The following article is presented in three parts. In Part I it is 

 proposed to give the general characteristics of the oscillation gap. In 

 Part II the oscillations are studied more in detail by means of Braun 

 tube oscillographs, and Part III contains a few practical considerations 

 and applications of the oscillations. 



