2^4 Seppings on a new principle of constructing 
2clly. That no free circulation of air can be obtained in these 
openings by any means. 
3dly. That timber being either freely exposed to, or ex- 
cluded from the air, is equally preserved. 
4thly. That it has been found on examining the frame and 
plank of old ships, that those parts (now filled in), generally 
decay sooner than the rest, viz. from the floor-heads in the 
midships, and from the deadwood forward and abaft to the 
height of the orlop clamps. 
If the above positions be true, it will follow, that by filling 
in these openings, much will be added to the durability of the 
ship; which also will be further promoted by omitting in these 
parts the inside plank, leaving thereby the surface of the 
frame timbers exposed to a free admission of air as often as 
the ship’s hold is unstowed, and by the filling in, excluding 
the air from two of the sides of every timber. 
By omitting the inside plank, much is added to the internal 
capacity of the ship’s hold. For though the trussed frame 
projects from the timbers more by five inches than the thick- 
stuff at the floor heads, yet, as in the old system, the per- 
pendicular riders are brought upon the thick stuff, their pro- 
jection into the hold is more by eight inches than that of the 
new, the advantage therefore as to stowage is in favour of the 
diagonal frame. A tier of iron ballast will also be disposed 
of in this principle many inches lower, whereby an increase 
of stability will be given with less weight, which will favour 
the ship in carrying her ports higher out of the water, inas- 
much as greater stability will be given with less ballast. 
An accurate conception of the state of the ship’s hold may 
be formed, by referring to the longitudinal section (PI. X. 
