52 Mr . Atwood's Propositions determining the Positions 
fluid, and external force is applied to incline it from its posi- 
tion, the resistance opposed to this inclination is termed the 
stability of floating. It is obvious to every one's experience, 
that some floating bodies are more easily inclined from their 
quiescent position than others ; that, after having been in- 
clined, some will return to their original situation with more 
force and celerity than others ; a difference particularly ob- 
servable in ships at sea, in some of which a given impulse of 
the wind will cause a much greater inclination from the 
perpendicular than in others. As this property of opposing re- 
sistance to heeling or pitching, when regulated to its due 
quantity and proportion, has been deemed of material conse- 
quence in the construction of vessels, several eminent mathe- 
maticians have been induced to investigate rules, by which the 
stability of ships may be inferred, independently of any refe- 
rence to trial, from knowing their weights and dimensions 
only. It must, however, be acknowledged, that the theorems 
which have been given on this subject, in the works of Mons. 
Bouguer,* Euler, - f Fred. Chapman, J and other writers, 
for determining the stability of ships, are founded on a sup- 
position that the inclinations from their quiescent positions are 
evanescent, or, in a practical sense, very small. But as ships 
at sea are known to heel through angles of io°, 20°, or even 
30°, a doubt may arise how far the rules demonstrated on the 
express condition, that the angles of inclination are of evanes- 
cent magnitude, should be admitted as practically applicable 
in cases where the inclinations are so great. 
* Bouguer. Liv. i. sec. iii. chap. iv. 
f Euler. Tbe'orie complette de la Construction et Manoeuvre des Vaisseaux, chap, 
iv. and chap. v. 
| Tr aite dela Construction des Vaisseaux par Fred, Chapman, chap. ii. p. 17. 
