§20 COMPARATIVE POWERS OF ELECTRICAL MACHINES. 



Exp. 2. The same arrangement as in the former ?x* 

 periment. The charge communicated by the Plate. IJie 

 discharge was produced by 138 turns, and the wire fused as 

 before. 



Exp. 3. The apparatus arranged as in the former expe- 

 riments. The two machines employed together to commu- 

 nicate the charge. The electrometer discharged itself in 

 65 turns ; the wire was melted as before. 

 The effects I" this last experiment the effect was produced in exactly 



casual, half the number of turns by the two instruments, that had 



been required by the most favourable action of one; and it 

 is perhaps impossible to conceive a more complete proof of 

 and the wire the similarity of their powers. The 48 inches of wire fused 

 measure^o/the m tnese experiments was afterward found to be a tolerably 

 sharge. exact measure of the force of the charge employed ; for on 



repeating the experiment with 4Q inches of the same wire, 

 it was barely rendered red hot. 

 The plate ma- Equal effects being produced by either machine in equal 



cbme more times, it became necessary to ascertain, whether any differ- 

 isisiW worked. . J ... 



ence existed in the power required to put them in motion. 



The handles were placed in a horizontal position, and 

 weights applied to them. 8lbs. troy were sufficient to move 

 the handle of the plate machine, but it required 14lbs. tq 

 produce the same effect with the cylinckr. 

 Some additions Here our first series of experiments terminated ; the re- 

 necessary, suits we had obtained had shown the necessity of some 

 addition to our apparatus, and we mutually agreed to defer 

 the farther prosecution of the subject, till these should be 

 supplied. In the mean time, some circumstances, which 

 had occurred in these experiments, continued to occupy 

 our consideration separately. Mr. Cuthbertson, as well as 

 myself, had been much surprised at the uniform action of 

 the two instruments; and the active discrimination with 

 which he considered the subject soon offered a means of in- 

 creasing and extending their powers, to an almost indefinite 

 extent. 

 Construction The cylinder machine we employed is constructed ov\ 

 ot u t cy iut.er. a ^ An \ believe to be peculiar to myself; it is entirely 

 insulated, in the manner of Mr. Nairne's; but the wo- 

 tiou is communicated by multiplying wheels with a sills 



cord, 



