326 LECTURE XXVIT. 



the ship, the curvature of the sails, or some other cause, throws the pressure 

 further backwards, and the action of the rudder is necessary to prevent the 

 ship's head turning towards the wind. (Plate XXII. Pig 2,95.) 



When a ship is steering in this manner on a side wind, the effect of the 

 wind has a natural tendency to overset her, and if she is too crank, that is, 

 deficient in stability, she cannot sail well, otherwise than directly before the 

 wind. The place of the centre of gravity, compared with that of the meta- 

 centre, or imaginary centre of pressure, determines the degree of stability, 

 and the most general way of increasing it is to lessen the weight of the 

 upper part, and of the rigging of the vessel, to diminish her height, or to in- 

 crease her breadth, and to stow the ballast as low as possible in the hold. 

 Too little attention has frequently been paid to this subject, as well as to 

 many other departments of naval architecture ; and although mere theore- 

 tical investigations have hitherto been but of little service to the actual 

 practice of seamanship, yet it cannot be doubted that an attention to what 

 has already been discovered of the laws of hydrodynamics, as well as to the 

 principles of mechanics in general, must be of great advantage to the navigator, 

 iii enabling him to derive from his own experience all the benefits, which a 

 correct mode of reasoning is capable of procuring him. 



