186 OUTLINES OF NATURAL PHILOSOPHY. 



This is not strictly true, except when the diameter of 

 the tube is very small : when the bore is nearly one- 

 tenth, the concavity becomes elongated on the lower 



''rf.4 ' 



274. When by inclining the tube, the column 

 of water is made to move, it appears to suffer re- 

 sistance as it approaches either end, and does not 

 completely reach the end, till the tube is either al- 

 together, or very nearly inverted. 



When the tube is placed in the water, however far 

 it be thrust down, the water within never reaches 

 the top, till the tube is completely immersed. 



275. If a capillary tube composed of two cylin- 

 ders of different bores, be immersed in water, first 

 with the widest part downwards, and afterwards 

 with the narrowest, the water will rise in both 

 cases to the same height. 



If the smaller end is such as to require the whole to be 

 filled by suction, the water stands at the same height 

 as if the whole tube were of the bore of the upper 

 part. This experiment, however, does not succeed 

 in vacuo ; and therefore the water in the wide part of 

 the tube, must be considered as sustained by the 

 pressure of the air. 



276. If two plates of glass be kept parallel, and 

 near to one another, and if their ends be immer- 

 sed in water, the water will ascend between them 



to 



