HYDROSTATICS. 189 



opposition to its gravity, the surface of which is 

 concave upwards, in consequence of the attraction 

 of the glass heing combined with the weight of 

 the water, and the cohesion of its particles. Hence 

 is derived the little meniscus of water, MIOKN 

 (%. 23.), which terminates the column. This 

 meniscus is, therefore, a body of water stretched 

 across the tube, and sustained there by the attrac- 

 tion of the glass, while it exerts its own attraction 

 on the particles of the column immediately under- 

 neath, by which means the gravity of those parti- 

 cles is diminished, and the water rises in the tube 

 above its level on the outside, to supply their defi- 

 ciency of weight. 



a. This is the theory of LA PLACE. He has deter- 

 mined the superficies of the meniscus to be nearly 

 spherical, and its attraction to be equal to that of a 

 spherule of water of the same diameter with itself, 

 supposing the attraction to be insensible at all sen- 

 sible distances. The ascent of the water, in the in- 

 verse ratio of the diameter of the capillary tube, is 

 thus accounted for ; the attraction of the meniscus 

 being directly as its diameter, or as the diameter 

 of the tube, that is, as the weight of the water sus- 

 tained. 



b. It is understood in all this, that the attraction of 

 the particles reaches beyond the nearest, but not to 

 any sensible distance, 



c. In 



