Ki 



M 



" 



i 

 J 



j 



| 



j 

 } 



'R 



touching his Theory of Light and Colours, 217 



play up and down so freely in the straight passage between 

 the bodies, as it could before they came so near together: 

 thus if the space of the aether's graduated rarity reach from 

 the body ABCDFE only to the distance GHLMRS, when 

 no other body is near it, { Yig. 2. 



yet may it reach fur- 

 ther, as to IK, when an- 

 other body NOPQ ap- 

 proaches ; and as the 

 other body approaches 

 more and more, I sup- 

 pose the aether between 

 them will grow rarer 

 and rarer. These sup- 

 positions I have so de- 

 scribed, as if I thought 

 the spaces of graduated 

 aether had precise li- 

 mits, as is expressed at 

 IKLM in the first figure, and GMRS in the second; for 

 thus I thought I could better express myself. But really I do 

 not think they have such precise limits, but rather decay in- 

 sensibly, and, in so decaying, extend to a much greater di- 

 stance than can easily be believed or need be supposed. 



5. Now from the fourth supposition it follows, that when two 

 bodies approaching one another come so near together as to 

 make the aether between them begin to rarefy, they will begin to 

 have a reluctance from being brought nearer together, and an 

 endeavour to recede from one another; which reluctance and 

 endeavour will increase as they come nearer together, because 

 thereby they cause the interjacent aether to rarefy more and 

 more. But at length, when they come so near together that the 

 excess of pressure of the external aether which surrounds the 

 bodies, above that of the rarefied aether, which is between them, 

 is so great as to overcome the reluctance which the bodies have 

 from being brought together ; then will that excess of pressure 

 drive them with violence together, and make them adhere 

 strongly to one another, as was said in the second supposition. 

 For instance, in the second figure, when the bodies E D and 

 N P are so near together that the spaces of the aether's gra- 

 duated rarity begin to reach one another, and meet the line 

 I K, the aether between them will have suffered much rare- 

 faction, which rarefaction requires much force, that is, much 

 pressing of the bodies together ; and the endeavour which the 

 aether between them has to return to its former natural state 

 of condensation, will cause the bodies to have an endeavour 



Phil. Mag. S. 3. Vol. 29. No. 193. Sept. 184-6. Q 



