

EXAMINATION OF VOLTA J S EXPERIMENTS, &C 285 



orafs plates of about fix inches ; c is a glafs cylinder fixed at 

 one end into a wooden foot d; e is a brafs ball, and mounting 

 at the other end to which the plate b b is fcrewed faft ; /is a 

 brafs wire with a joint at its lower end, and at the other end a 

 ball to which the plate a a is fcrewed, Handing parallel to b b. 

 By means of the joint, the plate a a may be moved back in the 

 fUuation of the dotted outline ag. The joint has a fhoulder 

 which flops the plate a a, and keeps it at its proper diftance 

 from b b. 



Fig. 3 is the common gold-leaf electrometer, with an addi- Bennetts leleftro- 

 tion of two vertical brafs plates of about 1 \ inch in diameter; ^denfcr. * 

 one is fcrewed faft to the brafs mounting at the top of the elec- 

 trometer, and the other to a wire which has a joint fixed to the 

 foot of the electrometer, by which it moveable, and is fet 

 either parallel and at a proper diftance from the other plate, 

 the joint being furnifhed with a flop for that purpofe, or may 

 be moved backwards in the direction of ga, fig. 2 : / is a brafs 

 cup with a fliank at the bottom, which fcrews into a hole in 

 the top oft?, fig. 2, ferving to examine the flate of electricity 

 excited by dropping of metals, &c. ; m is a flick covered with 

 tinfoil, which fcrews into the hole at e, to examine the electri- 

 city of the atmofphere ; n is a brafs wire jointed at o, with a 

 fliank, which can alfo be fcrewed into e when required, or into 

 the top of the gold leaf electrometer, fig. 3. Thefe two in- 

 ftruments, fig. 2 and 3, are ufed feparately or combined, as 

 the nature of the experiment may require. When the experi* 

 ment requires the aid of both condenfers, they are combined, 

 as is reprefented fig. 4, the two fixed plates flanding towards 

 the eye. The fixed plate of the large condenfer has a fmall 

 brafs pin at one fide, which, when the inftruments are ufed 

 together, mufl touch the fixed condenfing plate of the gold-leaf 

 electrometer *. 



THE METHOD OF USING THE DOUBLE ELECTRICAL 

 CONDENSER. 



Tojheiv the Ekclric Fluid excited by Efftrvefcence, Szc. 

 Screw / into the top of the ball e of the large condenfer, and Ufe of the two. 

 fet therein a china or glafs cup with proper ingredients for that ^ n ^5 nfers * 



* Inftead of gold leaf Mr. Read ufes very fine fibres of flax, which eff^S/ce 111 

 he thinks more feniible than gold leaf j but they are very difficult to & c . 

 be feen, and more eafdy deranged. If gold leaf be properly managed, 

 I think it preferable.— C. 



purpofe ; 



