3 So

HISTORY OF MARINE ARCHITECTURE.

shewn, is disabled from carrying s.iil : if it be too low, or divided and placed toonearthe extremities of the head and stern, it will acquire too sudden a motion, whichwill cause it to roll, as well as create other difficuhies and inconveniencies thatare not of less magnitude. By giving, in the latter instance, too great a momentumor weight to the head and stern, the vessel will be rendered extremely liable topitch, which causes one of the greatest impediments that can exist, in oppositionto the velocity of a ship’s passage through the water.

Stability, which has been already defined as the power derived by a vessel, oflaying her course with the least possible deflection, notwithstanding the opposi-tion of the wind, is effected primarily, in the shipping of most countries by theform of the hull itself, and secondly, as in the case of some peculiar classes ofvessels, belonging to the United Provinces, and other nations who have followedtheir example, by the application of a lee board which remedies the inability ofthe former to perform its own required service. No series of experiments appearsto have been made for the investigation of this point, or if made, they have not beenpublicly divulged to the world. The questions are simple, the expence trivial, andthe labour of a few hours would probably suffice to render the most virulentattempt of scepticism silent. Let six or more boards, having all exactly the samesurface and thickness, but of different forms, be drawn through the water with agiven weight; let the first experiment, for instance, be made on a board two feetsquare, and let the same be progressively continued, till the last is made with aboard eight feet in length, and six inches in depth. Then will the board that isdrawn through the water with the least velocity, point out the proportionatesurface, in respect to length and depth, which that part of the hull of a vessel,exposed to the fluid, that is to say. under the surface of the water, ought to have.This is the first principle only, and like all others of the same description, pointsout only the principium of the service, without descending to those minutias whichit is necessary should be ultimately digested, and enquired into, critically. It isnot only possible, but certain, that two vessels, exposing exactly the same surfaceto the water, and in the same manner, shall vary considerably in the propertyof being Weatherly. A full bodied vessel is infinitely less capable of holding adirect course than one of lanker description. The reason is obvious. The oppo-sition to the water is in the former instance oblique ; in the latter it at leastapproaches more nearly to a direct line. If it were possible to saw a vessel longi-tudinally down the center, and having carefully planked up, and caulked the aper-ture so that it should be water tight, to add such a counter-ballance by means of