of Ships of the Line* d4S^ 



(ii^advautageous effects J produced on the stability by the great 

 increase of moment incurred by every additional tier of guns, 

 not only by their simple weight, but also by their greater height 

 above the water's surface, and also by the weight of an addi- 

 tional deck and height of topside. The inclining power of the 

 wind on the additional height of topside in a three-decker 

 being greater than that, on an equal surface, of a two-decker 

 of the same force ; and the quantity of sail of the former being 

 elevated by a whole interval between deck and deck, constitute 

 additional reasons why a three-decked ship requires a greater 

 quantity of stability for the same surface of sail than a two- 

 decked one. One obvious method of counteracting this ten- 

 dency to instability, and that most usually resorted to, is to 

 add weight below the water plane ; but the use of ballast as a 

 corrective is to be avoided ; for, in a given ship, unless some of 

 the stores are discharged, the vessel must be more submerged, 

 and the lower ports brought nearer to the water than before*, 

 thus producing the long train of evils attendant on such a 

 circumstance. The only certain way of ensuring success in 

 this particular, is to give a suitable increase to the dimensions 

 of the ship, and a proper conformation to the sides between 

 wind and water; and happily the means by which we can 

 obtain a good height of battery are capable, in the hands of a 

 skilful constructor, of being made conducive to the acquire- 

 ment of a proper and permanent stability. It is very common 

 to hear persons ignorant of. the theory of naval architecture 

 assert, that the mere breadth of beam is sufficient to make a 

 stable ship; this is, however, but a very loose maxim. It is 

 partially true, but not generally so: — it is possible for a ship 

 with less breadth of beam than another, but having all other 

 circumstances the same, to possess a greater stability than the 

 latter. The truth is, that the area of the plane of floatation, 

 and the conformation of the sides between wind and waterf, are 

 the dominant elements in the determination of this property, 



* It should be an object to have as little ballast as possible, and io make the 

 heavy stores in the hold act as much as we can in that capacity. The introduc- 

 tion of iron tanks for the water, and iron chains instead of hempen cables, are very 

 favourable to such a disposition ; the shot, too, ought to be stowed so as to efl'ect 

 the same purpose. 



f AtwOod's Disquisition on the Stability of Ships. Philosophical Transactions 

 ftffl798, part2d.'.'> J. 1!>jU : -'IK ^ i-.n!-?'? o 



