310 Dr, Young's Remarks on the 
to the forces of the wind and waves; The effect of the wind 
is generally compensated by a change of the situation of the 
actual water line, or line of fluitation, so that its amount may 
be estimated from the temporary or permanent inclination of 
the ship ; and the force of the waves may be more directly 
calculated from their height and breadtli. These two forces 
can seldom be so applied, as to combine their effects, in 'pro- 
ducing a strain of the same kind in their full extent; it will 
therefore be sufficient for our purpose to determine the pro- 
bable amount of the force of the waves, which is more materially 
concerned in afiecting the longitudinal curvature than that of 
the wind. As a fair specimen of the greatest strain that is 
likely to arise from this cause in any common circumstances,, 
we may consider the case of a series of weaves 20 feet in height, 
and 70 in breadth ; the form being such, that the curvature of 
the surface may be nearly proportional to the elevation or de- 
pression : a single wave might indeed act more powerfully than 
a continued series, but such a wave can scarcely ever occur 
singly. We shall then find upon calculation,* that the greatest 
* The strain, produced by the pressure of waves of given magnitude, may be cal- 
culated from the comparison of the displacement with respect to their surface, 
compared with the displacement with respect to a level surface. It is true that the 
pressure upon the ship’s bottom is not immediately derived from the temjiorary height 
of the nearest portion of water ; but the horizontal motion of the water, which is the 
proximate cause of the elevation, is equally capable of affecting the fluid under a 
floating body, and of causing a pressure against it: the effect being nearly similar to 
the transmission of sound through an elastic medium. In other cases, the actual 
height of the fluid, over every particle concerned in the transmission of a wave, has 
been supposed, in calculations, to determine the pressure on it : but, whether from 
the necessary constitution of a fluid, or from the imperfect fluidity of fluids actually 
existing, it appears that there is a lateral communication of pressure w’ithin a certain 
angular extent, somewhat like the lateral friction attending the motions of fluids ; and 
