from Dr. TJiornlon. 231 



according to their several natures and dispositions, are en- 

 dued with peculiar attractive powers lij which they suck in 

 various juices from the blood. 



" That the glands of animals have sucli attractive pow- 

 ers, I shall prove from experiments and observations: 



" ' li'two plane polished plates of glass (suppose two pieces 

 of a polished looking-glass) be laid together^ so that their 

 sides be parallel and at a very small distance from one an- 

 other, and then their lower edges be dipped into water, the 

 water will rise up between them. And the less the distance 

 of the glasses is, the greater will be the height to which the 

 water will rise. If the distance be about the hundredth 

 ■ part of an inch, the water will rise to the height of about 

 an inch 5 and if the distance be greater or less in any pro- 

 portion, the height will be reciprocally proportional to the 

 aistance verv nearly. The weight of the water drawn up 

 being the same, whether the distance between the glasses 

 be greater or less, the force which raises the water and sus- 

 pends it must be likewise the same, and suffer no change 

 by changing the distance of the glasses. And in like man- 

 ner, water ascends between two marbles, polished plane, 

 when their polished sides are parallel and at a very little 

 distance from one another. And if slender pipes of glass 

 be dipped at one end into stagnating water, the water will 

 rise up within the pipe, and the height to which it rises 

 \\ill be reciprocally proportional to the diameter of the ca- 

 vity of the pipe, and will equal the height to which it rises 

 between two j)lanes of glass, if th.e semi-diameter of the 

 cavity of the pipe be equal to the distance between the 

 planes, or thereabouts. And these experiments succeed 

 akcr the same manner in vacuo as in the open air, (as hath 

 been tried before the Royal Society,) and therefore are not 

 influenced by the weight or pressure of the atmosphere/" — 

 See Newt. Opt. p. 306, 367. 



" Now, since the rise and suspension of water between two 

 glass planes, and in small glass' pipes, are not owing to the 

 pressure of the atmosphere, they must be caused by an at- 

 tractive power in the glass proportional to the weight of 

 Avater sustained by it. Let II, h denote the heights of the 

 column of water sustained between the two glass planes and 

 ot the cylinder sustained in a small glass pipe; B,p the 

 brcadlh of the column and periphery of the cylinder; and 

 D,d the thickness of the column and diameter of the cv- 

 liiider : and then the attractive power which sustains the 



culuinn will be as HBD, or as B, because H is as — j and 



V i the 



