of Small Floating Bodies. 421 



that the excess of hydrostatic pressure due to the difference of 

 height equivalent to o n or o' »', is made a pulling force, urging 

 B or B' to the right ; while the excess of hydrostatic pressure 

 due to the difference height equivalent to kr, is made a pushing 

 force urging A or A' to the left. Now, why this difference in 

 the direction of action of the excess of hydrostatic pressures? 

 Why not regard the excess of pressure on the right of B or B', 

 (equivalent o n or o' u'\ as a poshing force urging B or B' 

 towards A or A'?— a result which is evidently at variance with 



In the second place, it is very clear, that the laws of hydro- 

 statics are so seriously modified t>\ the action of capillary 

 forces (the disturbances of level being in fact due to them), 

 that it is very question: jsure can be 



properly or safely invoked to explain these phenomena with- 

 imposed by the introduction of the nega- 



u '- and positive molecular pressures, which constitute such 

 important factors in the physico-mathematical analyses of 

 these questions. 



In the following explanation of the "Apparent Attractions 

 and Repulsions of Small Floating Bodies," I have referred this 

 class of the phenomena to two fundamental principles of capil- 

 !;| ntv which are abundantly verified hv observation and exper- 

 iment, viz : 1st. That in every case, whether of moistened or 

 non -moistened bodies, there exists an adhesion between the 

 solid and the liquid ; and 2d. That the capillary forces are, 

 in any given case, inversely proportional to the radii of curva- 

 ture of the meniseoses, and their resultants are directed toward 

 the centers of concavity. It seems to me that these two fun- 

 damental atid well-established principles of capillary action, 

 will explain the whole class of phenomena, in a much more 

 consistent and satisfactory manner. 



Case 1. Fig. 1. Before the two bodies are brought near each 

 other, the concave meniscus around each of them having the 

 f'tne m.lius of curvature on all sides, each of the floating 

 bodies is in equilibrium under its action. But when brought 

 Sl) tiear tin n each other, the radius of cur- 



vature of the united intervening concave meniscus at <„. (tig. 

 ')■ is less than that of the exterior concave nteniseuscs at n and 

 °, and its superior tension acts upon both bodies toward a com- 

 mon center of concavity at 5. Hence, by virtue of the smaller 

 radius of curvature of the intervening tense film, the interior 

 forces prevail, and the two bodies are drawn together. 



Case 2. Fig. 2. The same explanation applies to this case. 

 The common or united intervening convex meniscus being 



