Chap. 2.] Small Eletfrical Machine. 317 



and dry. A bar of iron (AB, Fig. 2.) infulated \vith 

 the cords of filk j, j, is placed over the globe S, 

 this bar fcrves as a conductor to the electric fluid *. 



A machine of a fimpler conftruction has been in- 

 vented in this country, and is represented in Plate 

 XXVII. Fig. i. In this inftrument a circular plate of 

 glafs is employed inftead of a globe. The plate P p, 

 is bored through the center, and mounted on an axis, 

 a a 3 of copper or hard wood, to which is fixed the 

 handle, a b. The axis is Supported by two vertical 

 polls of wood, m, n, to which are appended four 

 cufhions, / z, formed according to the preceding di- 

 rections, and which ferve by their friction to excite 

 the plate. 



Before the plate a metal conductor, E D, is placed 

 horizontally, having two arms or branches, A B, alia 

 of metal, each terminating in a fmall globe or knob, 

 which may be brought within a convenient diflance 

 of the plate to receive the electrical fluid. The con- 

 ductor itfelf is infulated by two glafs pillars, F G. 



The advantages of this machine are, that it may be: 

 made portable, and is of fo fimple a conftruction, that 

 any gentleman in the country, after procuring a plate 

 of a reafonable thicknefs from a glafs houfe, may, by 

 the aid of a common cabinet-maker, conftruct one 

 for his own ufe ; the conductor may be equally infu- 

 lated by rofin, wax, filk, or any other electric or non- 

 conducting fubftance. 



This machine is, however, feeble in its operations,, 

 .compared with thofe constructed with globes or cy- 

 linders. The moil powerful, and yet the moft fim- 

 ple, of thefe that I have feen, are thofe defcribed by 



* Briflbn, Traitc elcmentaire de Phyf. torn. iii. p. 305. 



my 



