26 Prof. A. Battelli and Mr. L. Magri on 



the discharges were capable o£ producing greater effects in 

 the former calorimeter than in the latter. 



We performed some new experiments, however, using 

 continuous currents, sent through the calorimeters at long- 

 intervals. 



The arrangement adopted for this purpose consisted in 

 closing the accumulator circuit by means of a pendulum 

 which carried a point entering a mercury beaker placed 

 below, in the position corresponding to the position of rest. 

 This pendulum was 2*50 m. in length and accomplished an 

 oscillation of 1*80 m. in 1*6 sec. 



The length of the mercury beaker was 1 cm., so that the 

 duration of the passage of the current was about ^§5 of the 

 interval separating two successive passages. 



With these currents so markedly intermittent we obtained 

 also between the amounts of heat evolved in the two portions 

 of circuit, the same ratio as obtained in the case of a con- 

 tinuous passage of current. 



We may therefore conclude that the indications of our 

 calorimeters are really due to the heat evolved in the metallic 

 wire. 



As we do not think it necessary to give here the tables 

 containing the results of the measurements made to ascertain 



the value of the ratio — n we record the final values derived 



P 

 from them, i. e., the means of three series agreeing well 

 with one another (p. 27). 



From an inspection of the table opposite it results that 

 the effective resistance of a spiral (ratio between the calorific 

 energy absorbed by the latter and the mean square of the 

 intensity of current) is greater than the effective resistance 

 offered by the same wire when drawn out into a straight 

 line. 



25. In order to test the possible influence of the neighbour- 

 hood of the spiral on this increase of resistance, we made 

 some experiments with four other spirals, a, h, c, cL and, by the 



method above mentioned, determined the ratio —.. The 



P 

 copper wires the spirals a, 6, c were constructed with had 

 equal length and thickness, whereas the spiral d contained a 

 greater length of wire. 



Simultaneously we investigated the possible influence of 

 the frequency of current, owing to the more or less con- 

 siderable capacities it inserts into the discharge circuit. 



