W7 



hj its action on themselves; and exerts itself equally to 

 prevent their approach on one side, as theic recession on 

 the other. I conceive the agency of these forces to be 

 ^this : that the plate of water is so strongly attracted by 

 the. surfaces nearly in contact, as to be kept from run- 

 ning off, and has its outer edge exposed to the weight of 

 the air; whose pressure is thus communicated to all th® 

 particles of the water, and, by its mediation, to the con- 

 tiguous surfaces of the mirror and polisher. And, though 

 all these are really coiB,pressed together, ,by the. surround*- 

 ing atmosphere, yet I conceive tliat: this i doesr n®!t hinder 

 their gradual separation • from being effected: because, as 

 fast as- that separation takes place on any side, the air 

 and water rush in between the surfaces, to fill up. the 

 vacuity, as it. iS( formed; and no farther resistance arises 

 to their dis^Ajuction, than what is owing to the viscidity 

 of the -fluid interposed, : and to the force of cohesion! 

 which latter .acts, in this case, quite difterent from any 

 external force of compression ; and prevails, as I appre* 

 hend„:.tQ. a small distance from the surface, diminishin« 

 in the ralio of some high poAver of that distance.* 



And 

 "■...'''•■ 



^^ If It were supposed, that the force of coEesioa is confined to the sur- 

 face of bodies, and acts only in the state of actual contact; it would be 

 •bai-d to conceive, why a drop of liquor should ascend,, in a conical gias?— 

 pipe, whose narrow end was elevated: since the drop ought, on this sup- 

 position, to be attracted as much by the surfkce below, as by that above it; 

 .and its weight ought to make it descend; and there would be nothing ta 

 ipake it spread beyond the space of contact which it occupies: whereas, if 



tbe 



