Oscillatory Discharges. 621 



The electrostatic machine had one electrode put to earth, 

 and the other electrode connected with one o£ the armatures 

 of a condenser by means o£ a wooden rod. 



The spark- and the metal spiral calorimeters were in 

 series with the circuit traversed by the discharge ; after this 

 had passed, the condenser was put in connexion with a 

 ballistic galvanometer in order to measure the residual 

 charge. 



If calorimetric determinations were not to be made, the 

 square or circle forming the metallic circuit was introduced in 

 the place of the metallic calorimeters, the spark passing in the 

 air. If, however, those measurements were also to be made, 

 three or four discharge-photographs were previously taken, 

 the spark-gap being next inserted in the calorimeter, and 

 after having once again produced discharges, simultaneous 

 readings of the metal spiral calorimeter, of the spark- 

 calorimeter, and of the electrometer were taken. 



After each series of these readings, the residual charge 

 was measured. The above readings finished, the spark- 

 photographs were often taken again. 



Part III. 

 General Results of Experiments. 



31. From the single elements, as determined by the 

 methods above mentioned, we next calculated the final 

 results of our experiments, as contained in Tables I. 

 to XI. 



In the first six tables the results of simultaneous measure- 

 ments of the period of oscillation, of the amounts of heat 

 evolved in the various parts of the circuit, and of the dis- 

 charge-potential are recorded. 



In Table VII. the periods of oscillation are wanting. 

 Tables VIII. to XI. are exclusively relative to measurements 

 of the periods of oscillation. 



In the Tables I. to VII. we have given, in addition to 

 the values of the explosive distance in millimetres and those 

 of the discharge-potential, the mean amount of heat Q, 

 evolved with each discharge in the spark, and that. Q 2j 



evolved in the metallic circuit, and the ratio -y 1 serving to 



deduce the resistance of the spark from the resistance of the 



