Naval ARCHITECTURE (continued)

Y. The knee of the head, or cutwater.

Z Z. The cheeks of the head.

a a. The cat-head.

M C. The rising line of the floor.

k u C. The cutting-down line, which limits the thickness of all the floortimbers, and likewise the heighth of the dead-wood afore and abaft.

u U W. The midship-frame.

a, b, c, d, e, f, g, h. The frames or timbers in the fore-body of the ship, i. e. before the midship-frame.

1, 2, 3, 4, 5, 6, 7, 8, 9. The timbers in the after-body, or which are erected abaft the midship-frame.

As the eye of a spectator is supposed in this projection to view the ship's side in a line perpendicular to the plane of elevation, it is evident that the convexity will vanish, like that of a cylinder or globe, when viewed a a considerable distance; and that the frames will consequently be represented by straight lines, except the fashion-piece abaft and the knuckle timber forward.

It has been already observed, that the plane of projection may be defined a vertical delineation of the curves of the timbers upon-the plane of the midship-frame, which is perpendicular to that of the elevation. It is necessary to observe here, that the various methods, by which these curves are described, are equally mechanical and arbitrary. In the latter sense, they are calculated to make a ship fuller or narrower according to the service for which she is designed, and in the former they are drawn according to those rules which the artist has been implicitly taught to follow, or which his fancy or judgment has esteemed the most accurate and convenient. They are generally composed of several arches of a circle, reconciled together by moulds framed for that purpose. The radii of those arches therefore are of different lengths, according to the breadth of the ship in the place where such arches are swept; and they are expressed on the plane of projection either by horizontal or perpendicular lines; the radii of the breadth-sweeps being always in the former, and the radii of the floor-sweeps in the latter direction. These two arches are joined by a third, which coincides with both, without intersecting either. The curve of the top-timber is either formed by a mould which corresponds to the arch of the breadth-sweep, or by another sweep, whole center and radius are without the plane of projection. The breadth of the ship at every top-timber is limited by an horizontal line drawn on the floor-plane, called the half-breadth of the top-timbers. The extreme breadth is also determined by another horizontal line on the floor-plane; and the lines of half-breadth are thus mutually transferable, from the projection and floor-planes, to each other.

The necessary data by which the curves of the timbers are delineated then are, the perpendicular heighth from the keel, the main or principal breadth, and the top-timber-breadth: for as a ship is much broader near the middle of her length than towards the ends, so she is broader in

Reference Works