of the Electrophorus o/'Volta. 



365 



handle, covered with sealing-wax, is screwed by its wooden 

 foot. 



With ordinary excitation, this instrument will yield loud 

 flashing sparks, two inches long or more, and speedily charge 

 considerable jars. The cover can be easily charged and dis- 

 charged 50 or 100 times in a minute, by merely setting it down 

 and lifting it up as fast as the operator chooses, or the hand 

 can work. In charging a jar or plate, I place one knob of 

 the connecting rods near the insulated surface of the jar or 

 plate, and the other some inches above the cover; then the 

 cover, being alternately lifted up and set down, the jar is very 

 quickly charged. 



One instrument, nine inches in diameter, which I have made 

 upon the second plan above described, has very often surprised 

 me by its remarkable power of retaining electrical excitation. 

 The following example seems worthy of notice: — Early in Sep- 

 tember 1832, this instrument was moved from a house in York, 

 where it had been for some time laid by, and brought to my 

 present residence, distant £rd of a mile. It was placed on a shelf 

 on my book-cases, where it remained untouched until the 23rd 

 of March 1833, and was then taken down, covered with dust. 

 It was found to be in a state of feeble excitement, so as to give 

 sparks visible in the day-light nearly Jth of an inch long. 



Basis of the sole a cast-iron disk. 



a. The place of a ball in the first method. 



b. The slip of tinfoil in the second method. 



c, c, c. 



Conducting wires, in the third method, which is pre- 



ferred. 



York, April 2, 1833. 



