288 Mr. Seppings on a new principle of constructing 
The use of these beams is to secure the sides of the ship, 
so as to prevent her upper works from spreading, and to keep 
that part which is under water from being compressed by the 
fluid. They are also the supports or bearers of the decks (or 
what we call in houses the girders for the floors) and must 
therefore be of such strength as to endure the weiglit of the 
cannon, and whatever else is to be placed upon them. The 
usual mode of fastening these to the sides, has, generally 
speaking, been merely local, by two angular pieces of timber 
or iron (called knees) bolted to each beam, and also to the 
sides of the ship, by which means they were only partially 
held to the side, and there was wanting that continuity of 
materials, and consequently of strength, which the new system 
gives. 
Between the beams and at right angles witli them are placed 
pieces of wood called carlings, and at right angles with these 
(consequently parallel to the beams) ledges, which correspond 
with joists in a house. The planks or flat of the deck (floor- 
ing) is laid nearly in parallel lines from head to stern, upon 
and at right angles with the beams, and is fastened to them 
and to the carlings and ledges by bolts, nails, or wooden pins, 
called treenails. From this statement it will appear evident, 
that the decks, according to the old construction, are in nowise 
connected with the sides of the ship. 
Having thus briefly described the common mode of ship- 
building, it will next be proper to point out such of its defects 
as the new principle tends to remove. 
In the first place, it will be perceived, that all the materials 
composing the fabric of a ship are disposed nearly at right 
angles to each other. 
