VOL. XXX.] PHILOSOPHICAL TRANSACTIONS. 335 



view may be thought sufficient to overturn our theory. For since a periphery 

 of the tube ed, fig. 13, is able to sustain no more than a column of the length 

 AF, contained in the same tube; how comes it to sustain a column of the same 

 length in the wider tube dc, which is as much greater than the former, as the 

 section of the wider tube exceeds that of the narrower? Again, fig. 14, if a 

 periphery of the wider tube dc be able to sustain a column of water in the same 

 tube, of the length bg ; why will it support no more than a column of the same 

 length in the narrower tube ed ? Which queries may also be made with regard 

 to the 1 1th and 12th experiments. 



The answer is easy, for the moments of those two columns of water are pre- 

 cisely the same, as if the sustaining tubes, ed and cd, were continued down 

 to the surface of the stagnant water ab ; since the velocities of the water, where 

 those columns become wider, or narrower, are to the velocities at the attracting 

 peripheries, reciprocally as the different sections of the columns. 



Exper. 13, fig. 17. — From which consideration arises this remarkable para- 

 dox, that a vessel being given of any form whatever, as abc, and containing 

 any assignable quantity of water, how great soever; that whole quantity of 

 water may be suspended above the level, if the upper part of the vessel c be 

 drawn out into a capillary tube of a sufficient fineness. 



But whether this experiment will succeed, when the height of the vessel is 

 greater than that to which water will be raised by the pressure of the at- 

 mosphere, and how far it will be altered by a vacuum, I may perhaps have the 

 honour of giving an account to the Society some other time, not being per- 

 fectly satisfied with those trials which 1 have hitherto had the opportunity of 

 making. 



Having discovered the cause of the suspension of water in capillary tubes, it 

 will not be difficult to account for the seemingly spontaneous ascent of it. For, 

 since the water, that enters a capillary tube as soon as its orifice is immersed, 

 has its gravity taken off by the attraction of the periphery with which its upper 

 surface is in contact, it must necessarily rise higher, partly by the pressure of 

 the stagnant water, and partly by the attraction of the periphery immediately 

 above that which is already contiguous to it. 



P. S. When this paper was reading before the Society, I found that our 

 president [Newton] was already acquainted with the above-mentioned principle; 

 and I have since met with several passages in the 3 1 st query subjoined to the 

 late edit, of his Optics, which plainly show that he was master of it when they 

 were written. 1 must do the same justice to Mr. John Machin, Prof, of Astr. 

 in Gresham College. To these two worthy persons I am obliged for the fol- 



