given in the Enclopoedia Britannica. 281 



the weight of the whole elevated fluid is proportional to the ho- 

 rizontal extent of the surface which causes its suspension. 



These assumptions appear to me inconsistent with all the ob- 

 served properties either of soUd or fluid matter. The first of 

 them, indeed, accords exactly with the observed non-distur- 

 bance of a fluid's surface, until a solid is brought into actual 

 contact with it. But although the action of the solid has only 

 an evanescent extent before contact, it does not therefore fol- 

 low, that after contact has taken place, its influence is not sen- 

 sibly extended ; neither can such a supposition be admissible 

 when it leads us to conclude, that a mass of matter is elevated 

 and sustained by a force appHed only at one extremity, and 

 which, therefore, does not pass through its centre of gravity. 



The subject is one of great importance, and I imagine that a 

 scrutiny of the reasoning may not be unacceptable. In con- 

 ducting this examination, I shall first demonstrate the inade- 

 quacy of the hypothesis to account for the phenomena, and 

 then attempt to indicate that error which has led the cele- 

 brated author of the above-mentioned paper to a conclusion ex- 

 actly opposite. 



Let AB represent the vertical face 

 of a solid partially immersed in a fluid 

 whose horizontal surface is CM, its 

 disturbed surface MLK. Having 

 traced a canal vertically from C to D, 

 thence horizontally to P, and after- 

 wards vertically upwards, to termi- 

 nate in the disturbed surface at L, 

 it is obvious, that the equilibrium of 

 the fluid contained in this or any 

 other canal, is essential to that of 

 the whole mass. Now the horizontal portion DP is ah-eady 

 in eciuilibrium with respect to all the attractions acting upon 

 itself, since the attraction of the plate is not supposed to ex- 

 tend so far, and it may therefore be regarded as the mean 

 of communication between the two vertical branches CD and 

 LP ; the pressure at the lower extremities of which must 

 tiius be equal. Now these pressures are caused, in the Jirst 

 place, by the weights of the two masses ; and, in the second, 

 by the attractions of the fluid upon the minute portions situated 



