VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 6Q\ 



of gravity of the vessel, and thereby of increasing its stability: but, on trial, this 

 increase was by no means sufficient ; the diminution of heeling measured 

 on the vessel's side being only 4 inches. After this and other ineffectual attempts, 

 the defect of stability was at length remedied by applying a bandage or sheathing 

 of light wood to the exterior sides of the vessel, from 1 foot to 4 inches in 

 thickness, extending throughout the whole length of the water line, and 10 feet 

 beneath it. 



This account shows that the theory of stability, restrained to cases in which 

 the angles of inclination, or heeling, are very small, cannot be relied on for 

 ascertaining the requisite stability of ships in the practice of navigation. It 

 must be supposed that the weight and dimensions of every part of this ship were 

 exactly known to the engineers, yet we observe that the instability was not 

 certainly ascertained, but suspected only to exist when the ship was first set 

 afloat in deep water; and after this defect had been discovered by the experiment 

 which has been related, the cause was sought for in vain, and the remedy at 

 length was stumbled on by accident, rather than adopted from any knowledge of 

 the principles by which the application of it might have been directed. It seems 

 allowable to suppose, that if rules for ascertaining stability correspondent to any 

 different angles of heeling, similar to those here demonstrated, had been applied 

 to the case in question, they would have discovered that an error in the form* 

 given to the sides of the vessel was the principal cause of the defective stability, 

 and would have suggested the remedy accordingly ; or rather would have pre- 

 vented the necessity of having recourse to it, by previously showing the original 

 defects in the plan of the ship. 



The force of stability by which ships, when inclined round the longer axis 

 from their position of equilibrium through different angles, endeavour to regain 

 that position, is to be considered in 2 points of view respecting the motion of a 

 vessel at sea ; first, in respect to the resistance by which it opposes any force 

 that may be applied to incline the ship, for instance, that of the wind ; in which 

 case the ship's stability, and the impulse of the wind, constitute a species of 

 equilibrium, as long as the wind continues of the same intensity. 2dly. The 

 force of stability is to be considered as operating on the ship, after the force by 

 which it has been inclined ceases, to restore the vessel to its upright position ; 

 the ship being continually impelled by the force of stability, revolves round an 

 horizontal axis, passing through the centre of gravity with an increasing 

 velocity, till it arrives at its upright position ; and afterwards with a velo- 



* Mr. Romme observes, p. 108, that the defect of stability in the Scipio was not occasioned hy 

 any want of breadth in the principal section of the vessel ; for other ships of the same force, i. e. 

 Le Magnifique, Le Sceptre, Le Minotaur, L'lntrepide, the breadths of which were the same, or 

 rather less, than that of the Scipio, carried their sail perfectly well. — Orig. 



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