344 ON PHYSICAL DATA 



to the powerful influence of large waves of water 

 and currents of wind. Euler, and all succeeding 

 writers on the stability of floating bodies, make 

 the following principle the foundation of their 

 enquiries, namely, that when a vessel is acted 

 upon by the horizontal force of the wind, the 

 vessel will turn round on a line which passes 

 through the centre of gravity of the body, while 

 the centre of gravity remains at the same distance 

 from the plane of flotation. This principle would 

 not be true, 1 believe, even if there was no friction 

 between the water and the sides of the vessel, but 

 there is, and to what extent, experiment only can 

 determine : the water in the case of a vessel float- 

 ing forms an inclined plane, and the friction of the 

 plane will prevent the vessel from sliding down 

 it with that freedom which the vessel would do 

 providing there was no friction whatever. This 

 defect in the theory of the stability of vessels, was 

 first pointed out by Professor Moseley. In order 

 to ascertain the distance of the line round which 

 the vessel oscillates from the plane of flotation, 

 it will be requisite to obtain from experiments the 

 amount of the resultant of the wind's force, and 

 the point where it acts upon the vessel, and also, 

 the same with respect to the resistance of the 



