- "The advantage or giving large dimensions to ships carrying a certain force, arises," says Mr. Morgan in an ingenious disquisition on this subject, contained in the third number of his ' Papers on Naval Architec ture,' from several causes. It enables them to possess great stability, and thereby to carry a great press of sail, with a comparatively small body immersed in the water; thus giving them a great moving force in pro portion to the resistance they experience in moving through the water, which must increase their rate of sailing. Large dimensions in proportion to the num ber of guns, gives fine quarters to the men in action. It also enables a finer form to be given to ships below the water, so that they may have a good entrance for ward, and a clean run aft to the rudder; and to have the form best calculated to present great lateral re sistance to the water, which prevents the ship from making much leeway. This form below the water, in connexion with great stability, is very beneficial in enabling the ship to beat off a lee shore.
The greater expense arising from the increase of dimensions is, however, a disadvantage which renders it desirable not to carry this principle far beyond ne cessary limits. The number and weight of guns a ship is intended to carry, must be the foundation of the design. The total weight of a ship being found, a corresponding displacement must be given, and the height of the lower tier of guns, when the ship is fully stored and provisioned, fixed at not much less than six feet from the water's surface. The number of guns to be placed on a deck being determined, with such a distance between them as naval officers have found to be sufficient to work the guns conveniently in action, and the necessary length given before the foremost and abaft the aftcrmost port, the least length which can be given to the ship is found. The breadth in proportion to the length must then be determined. so that the stability may be sufficient to work the lee ward guns in a strong wind. The draught of water being then determined, such as experience has found to be necessary to keep a ship of such a class up to the wind, the form of the body may be given accord ing to the judgment of the constructer, the best cal ciliated for producing the necessary qualities of velo city, lateral resistance, answering the rudder readily, Sr.c. Should the total displacement be then found equal to the weight of the ship, the dimensions are deter mined according to the necessary limits. Whatever increase of dimensions beyond these limits may be given, to alter any particular property, must be at the disadvantage of additional expense.
From these tables also may be seen, the relative proportion between the length and breadth of the ships of different nations. The determination of the breadth to be given to any ship of which the length is fixed, is one of the most important considerations in the de sign. It is this dimension which principally affects
the stability of ships,—a quality on which the effici ency of a man-of-war, as well as its safety, depend. Although in order to determine the true value of the moment of stability, it is necessary to find the correct volumes of the parts immersed and emerged by the inclination, yet the breadth being the principal ele ment. in the determination of the value of this pro perty, a tolerably correct judgment of the relative sta bility of ships, if not very dissimilar in form, may be generally obtained by comparing their relative breadths. This property, ceteris paribus, continues Mr. Morgan, is proportional to the length and third power of the breadth; so that a very small addition to the breadth increases the stability as much as a 2 C 2 very considerable addition to the length. The advo cates for great length in proportion to the breadth of ships, assert that long and narrow ships are the fastest sailers. With the same moving power, that is, with the same quantity of sail, the long and narrow ship, under some circumstances, particularly with the wind aft or but little on the quarter, in light breezes and a smooth sea, may sail faster than a broader and shorter ship. But when a ship sails with the wind at any point between the limits of being close-hauled and on the quarter, the ship is necessarily inclined by the power of the wind on the sails, and requires sufficient stability to prevent the inclination becoming too great. A deficiency in stability is frequently of the most seri ous consequence: it may cause the loss of a ship on a lee-shore: it may preNent a ship in a stiff breeze, when engaged with an enemy, from using the leeward guns; in a chase. it may render a ship incapable of carrying the necessary press of sail to come up with the enemy by a ship heeling much, it brings the round part of the body into the water, and the keel and lower parts of the body, which oppose the greatest lateral resist ance to the water, become more oblique to its direc• tion, and the ship is consequently allowed to fall to leeward Inure than it would if less inclined; the effect of the force of the wind on the sails is also diminish ed by its direction being more oblique when the ship is inclined. The importance of a ship possessing great breadth in proportion to the length. to ensure sufficient stability, appears under these circumstances much more than to counterbalance the advantage, which, by having greater length in proportion to the breadth, might be obtained in velocity in light winds and a smooth sea. It may be observed,_ that too great stability is, on the other hand, dangerous by the great strain it brings on the ship, and the liability it gives of carrying away the masts. But this is an ex cess which is very rarely complained of; the more fre quent defect appears to he a deficiency in this quality.