Chap. 2.] Machines. 319 



On the top of the pillar O P is a conductor, which 

 is conne&ed with the cufhion, and this is called the 

 negative conductor. In both figures this conductor 

 is fuppofed to be fixed clofe to the culhion, and to 

 lie parallel to the glafs cylinder. In Fig. i. it is 

 brought forwards, or placed too near the handle, in 

 order that more of it may be in fight, as at R S j in 

 Fig. a. the end R S only is feen. 



Y Z (Fig. I. and 2.) reprefents the pofitive prime 

 conductor, or that which takes the electric fluid im- ' 

 mediately from the cylinder, L M the glafs pillar by 

 which it is fupported and infulated, and V X a wooden 

 foot or bafe for the glafs pillar. In Fig. i. this con- 

 ductor is placed in a direction parallel to the glafs 

 cylinder ; in Fig. i. it ftands at right angles to the 

 cylinder : it may be placed in either pofition occa- 

 fionally, as is moft convenient to the operator. 



Previous to relating feveral circumftances, by which 

 a large quantity of the electric fluid may be excited, it 

 may be neceflary to premife, that the refiflance of the 

 air feems to be leffened, or a kind of vacuum is pro- 

 duced, where the cufhion is in clofe contact with the 

 cylinder ; and that the electric matter, agreeably to 

 the law obferved by all other elaflic fluids, is prefied 

 towards that part where it finds lead refiftance } the 

 fame inftant, therefore, that the cylinder is feparated 

 from the cufhion, the fire iflues forth in abundance, 

 becaufe the refiftance made to it by the action of the 

 atmofphere is lefiened at that part : the effect which 

 ariles from the deftruction of the attraction or cohe- 

 fion between the cylinder and the cufhion is a further 

 proof of the truth of this hypothefis. The more per- 

 fect the continuity is made, and the quicker the folu- 

 tion of it, the greater is the quantity which will pro- 

 ceed from the culhion. 



' To 



