a rapid succession of Electrical Discharges, 333 



it with the same rapidity as with the coil ; but as this was im- 

 practicable, I had recourse to another expedient. I first ascer- 

 tained the effect produced upon the thermo-electrometer by 

 single discharges of the coil, from a jar containing a square foot 

 of surface, and I found these to be about 1 degree on the scale 

 for each discharge ; and if the discharges were made to follow 

 each other in succession as rapidly as would admit of their being 

 counted, I found that up to a certain point the degrees indicated 

 were nearly as the number of discharges. 



My next step was to ascertain if the same amount of charge 

 in the jar from the electrical machine would produce the same 

 effect; and having found this to be the case, 1 mounted the jar 

 with a Lane's discharger, the balls of which were adjusted so as 

 to produce a discharge of the requisite strength, a thermo-elec- 

 trometer being made to complete the circuit. As no electrical 

 machine would charge a jar with suflScient rapidity, I thought 

 of accumulating a powerful charge in a large battery, and of 

 drawing off the electricity rapidly from this reservoir into the jar 

 by means of a point, and succeeded admirably as far as the limits 

 of the charge would allow. I arranged on a table a battery of 

 thirty square feet of surface, and connected it with the electrical 

 machine, and upon a separate table placed the square-foot jar 

 with its discharger and thermo-electrometer, but without any 

 metallic communication between its outer coating and that of 

 the battery. I connected with the charging wire of the jar, by 

 means of a chain, a pointed wire fixed on an insulating handle, 

 and by this means, when the battery was charged, I could, by 

 approximating the point more or less rapidly to the conductor 

 of the machine, cause the small jar to become charged and to 

 discharge itself in rapid succession until the charge of the 

 battery was reduced to the tension expressed by the discharg- 

 ing interval of the small jar. In this way I succeeded in 

 obtaining as many as twenty and thirty discharges, and found 

 the effect to correspond precisely with that of the coil. When 

 passed slowly, the fiuid would rise 1 degree for each discharge 

 and sink again; if discharged a little more rapidly, so as to 

 pass each succeeding one before the effect of the former had 

 quite subsided, there was a corresponding accumulation of effect 

 upon the total number. If the point were approximated quickly, 

 so as to obtain the discharges in rapid succession, then the effect 

 was, as near as could be ascertained, in proportion to the sum of 

 the discharges. JNIy principal object at the time having been 

 simply to ascertain if the establishment of the same conditions 

 in the two cases would produce similar results, I did not investi- 

 gate the difference between the effect produced by this subdivision 

 of the charge of the battery and that which would have resulted 



