u Skin" -effect in Electrical Oscillators. 7 



ner walls gave still smaller effects. The knobs connected to 

 the machine* might, however, quite as well be hollow as solid, 

 and also, within certain limits, might be of less or greater 

 diameter without the efficiency of the oscillator being thereby 

 affected." 



As just remarked, these are the only references to the sub- 

 ject that I have found. Indeed, considering the importance 

 of the oscillating doublet, it is somewhat surprising that so 

 little has been done in the direction of a satisfactory theory 

 of it. 



2. The Oscillators. 



The oscillators were of two types, — cylindrical and spherical, 

 respectively. The cylinders were circular in section with hem- 

 ispherical ends; and were 2*5 cms in diameter and 12'5 cms long. 

 For exciting the oscillator an induction coil capable of giving 

 a 12'5 cm spark was used. It was placed in a metal-lined box 

 and connections were made to it as follows. 



OSCILL ATOt 



The cylinders C, D (figs. 1, 2) were placed along the focal 

 line of a parabolic reflector M, made of sheet zinc, being 

 held in position by wooden supports hollowed to receive them. 

 To the ends of the wires LL, were soldered strips r, r of brush 

 copper about 5 mm wide bent into circular form as shown in Gr 

 (fig. 2). The ends of the cylinders were slipped into these 

 copper holders, and a rubber band placed about the holder 

 drew it closely to the cylinder, thus insuring good and ample 

 contact. The wires were then led through a wooden block R 

 (shown in fig. 2), into which they were securely wedged, and 

 then through small glass tubes firmly held together by rubber 

 tape ; and were finally joined to A and B, the terminals of the 

 secondary of the coil. The glass tubes passed through open- 

 ings in the mirror M and the box. By this arrangement a 

 pair of cylinders could be removed and another pair substi- 



* Influence electrical machine. 



