666 Transactions. — Miscellaneous. 



first, and up to 21°, but after that she gradually lessens her re- 

 sistance, and at last the least pull turns her over. A very simple 

 analogy will illustrate this question of "range of stability." If, 

 while I am standing up, a pressure is applied sideways to my 

 right shoulder I shall be in danger of falling to the left. Bub 

 as long as it is possible for me to move my left foot outwards 

 in a direction opposite to the pressure, and to continue doing 

 this as the pressure is increased, I shall be able to make a 

 prolonged resistance. But if anything obstructs the outward 

 movement of my foot at any point it makes me unable any 

 longer to resist the pressure, and I must therefore fall. In 

 lieu of the outward movement of the foot, a vessel has to 

 depend upon the increasing support afforded by the leeward 

 movement of her centre of buoyancy. This can only be main- 

 tained as long as her form above water is such as to continually' 

 increase with each addition to the inclination the moment of 

 the area of that side of her section. The low freeboard of the 

 " Captain," as we have seen, first checked the due increase of 

 that moment, and then began to seriously undermine it. 



All that has so far been said upon stability refers only to 

 the measure of the energy with which a ship endeavours to 

 regain the vertical position. This is known as " statical 

 stability." I have shown, when a ship is careened to and held 

 at a given angle by the force of the wind, that a condition of 

 equilibrium between the two forces of wind and stability has 

 been attained. Such a condition might also be produced at 

 the same angle by suspending a large weight from, say, the 

 mainyard-arm. It would have to be adjusted as follows : 

 Suspend a plumb-line from the yard-arm and measure the 

 horizontal distance from it to the centre of gravity of the ship ; 

 then divide the stability measure expressed in foot-tons .by 

 this distance. The result will be the number of tons which 

 must be suspended from the yard-arm to produce the given 

 inclination. It is a simple question of balancing, and may be- 

 compared to the before-mentioned case of an ordinary steel- 

 yard, where a large weight is balanced by a small one having 

 greater leverage. The moment of each acting at the fulcrum 

 balances the other, and is equal to its weight multiplied by 

 its distance from the fulcrum. In the case of the ship the 

 moment is spoken of as being equal to so many foot-tons ; in 

 the case of the steelyard it might be termed inch-pounds. 

 While this measure indicates the steady resisting-power of a 

 vessel, yet it does not express the whole problem, seeing that 

 it takes no account of the work performed in bringing about 

 the careening. It generally happens that the act of careening 

 raises the centre of gravity of the vessel, or, in other words, 

 that it lifts her whole weight to a higher level. Such an effect 

 cannot be produced without an expenditure of power. This 



