23- Letter to Governor Pownall 



the attractive power which sustains the cylinder will be as 



hpd p , u • 1 



— i- , or as — , or as p, because h is as — -. 



" Hence it appears that the attractive power which sustains 

 the water arises only from those parts ot" the glass which are 

 contiguous to the surface ot the elevated water ; or, more 

 truly, from the parts of a narrow surface of the glass,^whose 

 lower edge touches the surface of the water, and whose 

 height is the small given distance to which the attractive 

 power, with which glass aitracts water, reaches ; and tliere- 

 fore the attractive powers of the glass planes and small glass 

 pipe will be as 2 B and p. But the powers are as the weights 



sustained by thcm^ that is, 2B. p :: HBD. ~: whence 



HD will be equal to -7-; and, when D is ecjual to — , II 



will be equal to h. 



'^ This power varies in one and the same pipe, or becomes 

 different when exercised on different fluids. For one and 

 the same small glass pipe will sustain different weights of 

 diiFerent fluids, as appears from this table. 



In 



