7$ Dr. Young’s Essay 
by the cohesion of the internal surface of the water exactly in 
the same manner as the form of a drop of water in the air. 
The delay of a bubble of air at the bottom of a vessel appears 
to be occasioned by a deficiency of the pressure of the water 
between the air and the vessel ; it is nearly analogous to the 
experiment of making a piece of wood remain immersed in 
water, when perfectly in contact with the bottom of the vessel 
containing it. This experiment succeeds however far more 
readily with mercury, since the capillary cohesion of the mer- 
cury prevents its insinuating itself under the wood. 
V. Of apparent Attractions and Repulsions. 
The apparent attraction of two floating bodies, round both 
of which the fluid is raised by cohesive attraction, is produced 
by the excess of the atmospheric pressure on the remote sides 
of the solids above its pressure on their neighbouring sides : 
or, if the experiments are performed in a vacuum, by the equi- 
valent hydrostatic pressure or suction derived from the weight 
and immediate cohesion of the intervening fluid. This force 
varies ultimately in the inverse ratio of the square of the dis- 
tance ; for, if two plates approach each other, the height of 
the fluid that rises between them is increased in the simple 
inverse ratio of the distance ; and the mean action, or negative 
pressure, of the fluid on each particle of the surface is also 
increased in the same ratio. When the floating bodies are both 
surrounded by a depression, the same law prevails, and its 
demonstration is still more simple and obvious. The repulsion 
of a wet and a dry body does not appear to follow the same 
proportion : for it by no means approaches to infinity upon 
the supposition of perfect contact ; its maximum is measured 
