PHYSICAL AND LITERARY. 27 



1 8. If that furface were perfedly fmboth, 

 the under furface of the drop would be fo 

 likeways ; and would therefore fhow an 

 image af the illuminating body by reflexion, 



like 



of the phisnomeaa may be ufeful towards fuch an enquiry. 

 Ca/e I. Suppofe a fluid which is attrafted to the fide of its 

 containing vefFel, and confequently is elevated, at the fides, 

 into a concave furface: If a body be immerfed which at- 

 trads the Huid, and is therefore furrounded likeways with a 

 concave elevation of the fluid ; as foon as the two elevations 

 begin to join, the body will move towards the fide of the 

 vefl'el with an accelerated motion. Cafe 2. Suppofe a fluid 

 which is formed into a convex furface, either by the repul- 

 five power of the containing veflel or cohefive force of its 

 own particles : If a light body be immerfed which attrads 

 the fluid ; as foon as its furxounding elevation begins to join 

 with the lateral depreflion of the fluid, it will begin to move 

 towards the middle of the veflel ; and, if it be brought by 

 force towards the fide, it will recede from it again with an 

 accelerated motion. 



In both the firfl: and fecond cafes, if the attrading 

 body be held fafl:, and the whole fluid made eafily moveable 

 with its containing velTel, it will remove to or from the at- 

 trading body in the fame manner as the attrafting body did 

 with refpeft tb it ; i. e. in the firft cafe, the wholp fluid will 

 move fp that the attrafling body may come to its edge j 

 and in the fecond, fo that it may recede from it. Cafe 3. 

 If, in a fluid which is attrafled by the fides of its veflel, a. 

 body be immerfed which repels the fluid, and is therefore 

 furrounded v/ith a ditch or convex depreflion of the fluid j as 

 foon as that depreflion begins to join the elevation of the 

 f^oid at the fides, it will recede tovyard$ the tniddlc ; and, if 



forcibly 



