94 Inquiries into the Principles of Liquid Attraction. 



will, when placed contiguous to each other, recede." When two 

 floating bodies which make opposite curves in the surface, the one 

 upward and the other downward, are placed contiguous on water, 

 these opposite curves have nearly a perpendicular position, and con- 

 sequently the contractile force of their curved surfaces acts in the 

 same direction, and in consequence of the direction in which this 

 force acts, it is unable to resist the force of the surrounding surface ; 

 and hence, the bodies recede from each other, one or two inches, to 

 jstations where the remote extremities of their opposite curves coincide 

 With the common surface ; and here the bodies remain at rest, unless 

 the momentum with which they were at first propelled, carries them 

 beyond these limits. (See Fig. 4.) 



' The ascent of liquids in capillary tubes, and between two parallel 

 plates of glass, takes place on precisely the same principle as in the 

 lifting pump. When two parallel plates of glass are partly immersed 

 in water, and are placed perpendicularly to the common surface, if 

 they have an elevation of the liquid around them, they will, when 

 brought sufficiently near together to have the remote extremities of 

 their elevated curves meet, have a column of water rising between 

 them, and the height to which it will rise increases in tlie same ratio 

 as the distance between the plates diminishes ; and for this reason ; 

 their focal seat of attraction has the same extent, and acts with the 

 same uniform force at all tlie different distances of the plates, and the 

 contractile force of the surface also continues the same, but it has the 

 pressure of a less column of atmosphere to resist, and this column of 

 pressure diminishes as the area of the surface between the plates di- 

 minishes. (See Fig. 12.) 



In capillary tubes of different bores, the focal seat of attraction di- 

 minishes as the diameters of their bores, but the pressure of the at- 

 mosphere which it resists, diminishes as the squares of these diame- 

 ters ; hence, as the diameters of capillary tubes diminish, the force of 

 the contractile surface which acts from the focal seat of attraction, 

 has a ratio to the force of the atmosphere constantly increasing, and 

 therefore as the bores diminish, the liquids ascend with this increas- 

 ing ratio. Now if a capillary tube be immersed in water, and then 

 be raised from the water in an inclined position, so as to take up a 

 greater quantity than it otherwise would, it will then sustain a column 

 about twice the perpendicular height that it will when the lower ex- 

 tremity of the tube rests in water ; for when the tube is taken from 

 the water, the pressure of the atmosphere is diminished by the upper 



