On some Improvements in the Construction 



OF CURRE'S DI-ElECTRIG MACHINE. 



By D. B. Adams ox. 



[Read February 6, 1883.] 



My object in coming before the Society on this occasion is 

 principally to detail a few experiments made by me in con- 

 structing the machine now before you. Being desirous of 

 rendering it as effective as possible, I took some trouble in 

 experimenting in various ways for that purpose. 



The machine is known by the name of " Curre's Di-electric 

 Induction Machine." It consists of two parts, one resembling 

 the common frictional-plate machine with its rubbers and 

 collecting comb ; the other of a larger disc overlapping the 

 former, and running as close to it as may be, without touching. 



The large disc acts the part of a di-electric between the 

 smaller one and the points of a comb which carries off the 

 electricity toward the prime conductor. The smaller disc, as it 

 passes between the rubbers, becomes charged with positive 

 electricity, and therefore, by induction, attracts negative 

 electricity from the points of the comb, which is deposited on 

 the large disc, and leaves the lower comb and its conductor 

 charged positively. The large disc, w^hich by means of the belt 

 and pulley is made to rotate eight times for every turn of the 

 smaller one, delivers up its charge of negative electricity as it 

 passes the points of the upper comb, and so the prime conductor 

 becomes negatively charged. 



By the upright rod which acts on a joint, the ball at the top 

 can be brought nearer to, or removed further from, the prime 

 conductor, so as to show the length of spark the machine can 

 produce. 



The wooden apparatus on the top forms no part of Curre's 

 machine, but is an addition of my own, and is a modification of 

 what is known as Winter's ring. 



Having finished the machine in the first place without this 

 appendage, although I found it gave out electricity in con- 

 siderable quantity, I was not satisfied with the length of spark, 

 which was seldom above five inches, and my first experiment 

 was on the slab of ebonite opposite the upper comb. This 

 appendage is by some makers supposed to lengthen the spark 

 by one-third. Others again who have tried it say it has no 



