Inquiries into the Principles of Ldquid Attraction. 93 



sented by ; because the water will rise no higher than about thirty 

 two feet. But the lateral pressure of the atmosphere at the same 

 height suffers no sensible diminution ; consequently the lateral press- 

 ure of a column of water, which can rise but about thirty two feet 

 by the pressure of the atmosphere, is unable to resist the lateral 

 pressure of the atmosphere at an equal height. From these facts, it 

 will be very readily understood ivhy two floating bodies, which have 

 an elevation of the liquid around them, approach each other. For 

 when the remote extremities of their curves of elevation meet, these 

 two curved surfaces, which in respect to the common level are be- 

 coming concave, now act as an upward moving piston diminishing 

 the pressure of the atmosphere, and consequently allowing the pre- 

 ponderating lateral pressure of the atmosphere, to force the float- 

 ing bodies toward each other. (See Fig. 10.) Now as these bodies 

 approach, the column of liquid between them rises, and the contrac- 

 tile surface constantly taking off* the atmospheric pressure, leaves the 

 column of liquid, whose lateral pressure diminishes with its height, 

 constantly less able to resist the lateral pressure of the atmosphere; 

 and on this account the bodies should come together with an increas- 

 ing velocity, which experiment abundantly proves. 



3rd. Let us notice the application of these principles to the fifth 

 law, viz : " two floating bodies, both having a depression of the liquid, 

 will, when near, approach each other with the liquid descending be- 

 tween them." When the surface of the liquid curves downward, the 

 same contracting force which, in elevated curves gave an upward mo- 

 tion, now acts with an equal force downwards, and the surface in this 

 case may be considered a piston, not of a lifting but of a forcing 

 pump. Accordingly, when two floating bodies, both of which have 

 a depression, are placed within about an inch of each other, the curves- 

 which tliey make, meet, and in respect to the common level of the 

 liquid, are becoming convex. The small column of liquid between 

 the bodies is now depressed below the common level, by the con- 

 tractile power of the surface, (See Fig. 5,) and the lateral press- 

 ure of the atmosphere, which supplies the place of the depression, is 

 now unable to resist the lateral pressure of tlie surrounding water, 

 and the bodies are consequently made to approach each other, with 

 a velocity which is increased as the distance between the bodies is 

 diminished. 



4th. As the principles respect the sixth law, viz : " two floating bo- 

 dies, one having an elevation and the other a depression of the liquid^ 



