CHAPTER XIII. 



OF THE STABILITY OF FLOATING BODIES AND OF SHIPS. 



446. IN the preceding pages, we have investigated and exemplified 

 the method of determining the positions of equilibrium in a few of the 

 most important cases, where the forms of the floating bodies are such 

 as to render them of very frequent occurrence in practical construc- 

 tions ; we shall therefore, in the next place, proceed to investigate and 

 exemplify the conditions of Stability, or that power, by which, when 

 the equilibrium of a floating body has been disturbed, it endeavours, 

 in consequence of its own weight and the upward pressure of the 

 fluid, either to regain its primitive settlement, or to recede farther 

 from it, by revolving on an axis passing through its centre of gravity 

 parallel to the horizon, until it arrives at some other position of 

 equilibrium, in which the principles of quiescent floatation are again 

 displayed. 



1. DEFINITIONS AND PROPOSITIONS OF STABILITY IN FLOATING BODIES. 



447. It is familiar to every person's experience, that when bodies of 

 certain forms and dimensions, placed under particular circumstances 

 on the surface of a fluid, have their equilibrium deranged by the 

 action of some external force, they return to their original position 

 after a few movements or oscillations backwards and forwards, in a 

 direction determined by that of the disturbing impulse. 



It is equally obvious with regard to other bodies, that however 

 small may be the quantity of their deviation from the original state of 

 quiescence, they have no tendency whatever to return to it, but con- 

 tinue to recede farther and farther from it, by revolving about a 

 horizontal axis, until the deviating effort obtains a maximum depend- 

 ing upon the angle of deflexion ; after which the deflecting energy 



