694 THILOSOPHICAL TRANSACTIONS. [aNNO I796. 



cularly the measure of the greatest stability, and the angle of heeling at which 

 it takes place. 



In these general remarks the water's resistance has not been considered, which 

 must necessarily have some effect in retarding tiie 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 from 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 mo- 

 tion ; whereas in the rolling of ships a far less quantity of water suffers an altera- 

 tion of place by the ship's oscillations, which are therefore the less retarded on 

 this account. 



Another observation occurs on this subject. The entire stability of a ship 

 has been shown to consist of the aggregate stabilities of the several 

 vertical sections into which it can be divided. Let it be supposed that 

 the sliip 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 sta- 

 bility ; 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 horizontal lines be- 

 tween the longer and shorter axes; a circumstance 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 vessels towards the latter end of the last cen- 

 tury, in a work intitled 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, particularly John Bernouilli, Bouguer, 

 and the excellent M. Euler, whose treatise, intitled Theorie complette de la 

 Construction & Manoeuvre des Vaisseaux, is a work correspondent to the title, 

 entirely theoretical. In this elaborate performance the author has not only en- 

 deavoured to explain the complicated laws which influence the motion of ships 

 at sea, but proceeds to investigate, on the ground of such data as the subject 

 affords, the dimensions and position of the most essential parts of vessels which 

 combine to give them every possible advantage in the practice of navigation. 

 Several inquiries are suggested by the perusal of these theoretical works; first^ 

 whether the proportions and dispositions of parts in ships resulting from theory 

 have been found to differ from, or to agree with, those which had been previously 

 establishetl in the practice of naval architecture; 2dly, if disagreement should 

 have been discovered, whether any adequate and satisfactory trials have been 



