676 Transactions. — Miscellaneous. 



respective centres of gravity, and then ascertaining what 

 change their moments must make in the ship's centre of 

 gravity. 



Another method may be adopted for ascertaining the centre 

 of gravity of a ship. It requires that she shall at the time be 

 drawing more water at one end than at the other, and it neces- 

 sitates the use of a graving-dock. If she is drawing more 

 water aft than forward her stern-post will take the blocks 

 first. As the water falls it will leave her after-body some- 

 what, but the fore-body will sink correspondingly deeper so as 

 always to maintain a condition of equilibrium between her 

 weight and displacement until she settles on the blocks all 

 along her keel. The after-keel block thus forms a fulcrum, 

 and the weight of the ship always presses downwards through 

 its centre of gravity. The centre of buoyancy can be calcu- 

 lated, and it is known that the centre of gravity of the ship is 

 vertically above it. The only question is. At what height up 

 is it situated? — and this can be worked out by a reliable rule. 



In conclusion, I wish to express the hope that I may not 

 have altogether failed in trying to give a popular explanation 

 of the leading principles of stability. It has been a very brief 

 sketch, although quite long enough for one evening's work. 

 The subject has been merely entered upon, and is one well 

 worthy of the close attention of all who are connected with the 

 building, sailing, or commercial management of shipping. 

 Theory is often sneered at, and practical experience extolled. 

 My aim has been to show that they may go hand-in-hand, 

 and, as an effort in that direction, I present the paper to the 

 New Zealand Institute. 



