614 
EXPERIMENTS ON THE STABILITY OF FLOATING BODIES. 
Master Shipwright of that dockyard, and Mr. Rawson were kind enough to under- 
take them. 
The details of these experiments accompany my paper ; they extend beyond the ob- 
ject originally contemplated by me ; and whether regard be had to the practical im- 
portance of the question under discussion, the great care and labour bestowed upon 
them, or the many expedients by which these gentlemen have succeeded in giving to 
them a degree of accuracy hitherto, I believe, unknown in experiments of this kind, 
they claim to rank as authentic and valuable contributions to the science of naval 
construction. 
10. That it might be determined experimentally whether the work which must be 
done upon a floating body to incline it through a given angle be that represented by 
equation 6, it was necessary to do upon such a body an amount of work which could 
be measured ; and it was further necessary to ascertain what were the elevations 
of the centres of gravity of the body and of its immersed part thus produced, and 
then to see whether the amonnt of work done upon the body equaled the difference 
of these elevations multiplied by its weight. 
To effect this, I proposed that a vessel should be constructed of a simple geome- 
trical form, such that the place of the centre of gravity of its immersed part might 
readily be determined in every position into which it might be inclined, that of its plane 
of flotation being supposed to be known ; and that a mast should be fixed to it, and a 
long yard to this mast, and that when the body floated in a vertical position a weight 
suspended from one extremity of the yard should suddenly be allowed to act upon it 
causing it to roll over ; that the position into which it thus rolled should be ascer- 
tained, together with the corresponding elevations of its centre of gravity and the centre 
of gravity of its immersed part, and the vertical descent of the weight suspended from 
the extremity of its arm. The product of this vertical descent by the weight suspended 
from the arm ought then, by the formula, to be found nearly equal to the difference 
of the elevations of the two centres of gravity multiplied by the weight of the body ; 
and this was the test to which I proposed that the formula should be subjected, 
having in view its adoption by practical men as a principle of naval construction. 
To give to the deflecting weight that instantaneous action on the extremity of the 
arm which was necessary to the accuracy of the experiment, a string was in the first 
place to be affixed to it and attached to a point vertically above, in the ceiling. When 
the deflecting weight was first applied this string would sustain its pressure, but this 
might be thrown at once upon the extremity of the arm by cutting it. A transverse 
section of the vessel, with its mast and arm, was to be plotted on a large scale on a 
board, and the extreme position into which the vessel rolled being by some means 
observed, the water-line corresponding to this position was to be drawn. The posi- 
tion of the yard, in respeet to the surface of the water in that position, would then be 
known, and the vertical descent of the deflecting weight could be measured, and also 
the vertical ascent of the centre of gravity of the immersed part or displacement. 
