Withy. — 0)i the Stability of Ships. 669 



as follows: "It will be necessary here also to make an 

 assumption — viz., that no hole exists in the part brought 

 under water by the act of careening the ship." In making 

 this reservation I had in my mind the case of the sinking of 

 the s.s. "Austral " in Sydney Harbour. For a long time after 

 that vessel was raised and sent to sea again a great deal of 

 prejudice existed as to her supposed want of stability. This 

 idea was entirely groundless ; and I believe that few safer or 

 better ships ever floated. The fact was that the covers had 

 been removed from the coaling-ports which pierced her sides 

 amidships ; coal was being introduced into her bunkers through 

 these ports, and the operation was continued until the vessel 

 bad sunk low enough for the water to enter them. The result 

 was inevitable. The introduction of a comparatively small 

 quantity of water would not only cause her to sink lower, and 

 so increase the inflow every moment, but would cause her 

 to become slightly unstable, and therefore probably to list 

 enough to cover the whole area of the ports very quickly. 

 The great inrush so caused would very soon sink her. Again, 

 in the case of a war-ship the piercing of the top-sides would, 

 if it led to an influx of water, very quickly alter the former 

 conditions of stability. Carelessness in leaving the cabin ports 

 of a passenger-steamer open in rough weather might soon 

 produce the same results. 



The third assumption was in reference to the form of the 

 vessel which I took for the purpose of careening. It reads as 

 follows: "It will simplify our work at this stage if we deal 

 with one cross-section of a ship — say, the midship one — and 

 assume for the moment that the vessel from end to end is of 

 that form." Of course we never see a vessel so shaped, but 

 the device enabled me to show the results of the change of 

 form effected by careening more simply by assuming them to 

 be concentrated in one representative section. You will 

 readily see that the portions immersed to leeward and emerged 

 to windward are not mere areas, as for the moment assumed, 

 but solid wedges extending the whole length of the ship, and 

 that, by reason of the fining of the lines and the alteration in 

 form of the vertical sections towards the bow and stern, these 

 are of irregular shape. On the strength of this third assump- 

 tion I made the following statement : "The triangle of immer- 

 sion in the given example is equal in area to the triangle of 

 emersion.'-' To understand the mtention of this, you must 

 substitute " solid " for " triangle," and understand the sentence 

 to read as follows : "The solid of immersion is equal in bulk 

 to the solid of emersion." 



To save myself from a possible misunderstanding, it maybe 

 as well, by way of endeavouring to state the fact exactly, to 

 make another slight reservation upon the last statement. It 



