Oscillatory Discharges* 



21 



Round the exterior recipient R there was wound a 

 sufficient layer of wool cloth, the whole being placed within 

 a wooden box C, and being capable of moving by means o£ 

 the arm NO, to which it was attached, along the brass rod A, 

 and being thus raised to different heights. 



the arrangement above described 

 to pass freely when taking the 



;e ol 



spar J 



We had to make Uf 

 in order to cause the 

 photographs. 



When photographs had 

 at the level shown in fig. 



pass freely when taking- 



be taken, 

 In order 



the box was fixed 

 next to insert the 



spark into the calorimeter it sufficed to raise the arm NO. 



Fig-. 6. 



A good closing of the two openings aa f of the calorimetric 

 recipient R was obtained by passing the brass rods D, D' of 

 the spark-gap through rubber tubes at the part near the inter- 

 ruption where the spark occurred. This method of closing- 

 allowed of placing the calorimeter in position with all de- 

 sirable facility and speed when the heat evolved in the 

 spark was to be determined. 



This form of calorimeter seemed more adequate than those 

 previously used by other experimenters, as we avoided the 

 trouble due to the explosive and electrostatic effects of the 

 spark. Moreover, we avoided the difficulties, met with in 

 the case of air-calorimeters being used, in the accurate deter- 

 mination of the part played by the expansion of the gas in 



