124 Mr. Atwood’s Propositions determining the Positions 
In these general remarks the water’s resistance has not 
been considered, which must necessarily have some effect in 
retarding the oscillations of the vessel, and more in the larger 
arcs than in the smaller: it is however observable, that the 
resistance to the rolling of vessels is of a very different kind to 
that which is opposed to their progress through the water, in 
which case a volume of the fluid proportional to the vessel’s 
bulk and velocity is entirely displaced during its motion ; 
whereas in the rolling of ships a far less quantity of water suf- 
fers an alteration of place by the ship’s oscillations, which 
is therefore the less retarded on this account. 
Another observation occurs on this subject. The entire 
stability of a ship has been shewn to consist of the aggregate 
stabilities of the several vertical sections into which it can be 
divided. Let it be supposed that the ship has been inclined 
round the longer axis through a given angle, and that the 
vessel returns through the same angle of inclination by the 
force of its stability ; if the forces arising from the several 
sections do not act in their due proportion on each side of the 
centre of gravity, in respect to the longer axis, the ship will not 
return to its position of equilibrium by revolving round the 
longer axis ; but will be inclined round various successive ho- 
rizontal lines between the longer and shorter axes; a cir- 
cumstance that must create irregular motions and impulses, to 
which a vessel in all respects well constructed is not liable. 
The theory of statics and mechanics was, I believe, first 
applied to explain the construction and management of ves- 
sels toward the latter end of the last century, in a work inti- 
tuled Theorie de la Construction des Vaisseaux, par P. Paul 
Hoste, printed at Lyons in the year 1696. Several eminent 
mathematicians have since prosecuted this difficult subject. 
