324^ Dr, Young^s Remarks on the 
the other two became more acute : but when the planks of the 
deling are laid in an oblique direction, they serve as diagonals 
to the rectangles, so that a simple change of the relative 
angular situations of the sides is not sufficient to admit of the 
arching, without an alteration of the length of the diagonals, 
which would afford a resistance incomparably greater, espe- 
cially at the upright parts of the sides, although at the floors 
it would have but little effect/' Traite du navire, 154. Mr. 
Groignard also, whose memoir, on the improvement of ship- 
building, has been obligingly communicated to me by an 
ingenious gentleman, formerly his pupil, although he objects 
to Mr. Gobert's method, confesses that he “ should have very 
much approved this mode of disposing the cieling, if it had 
been possible to employ straight planks, having the same 
obliquity without interruption, throughout the whole of the 
ship's length but thinks, with Bouguer, that in carpentry, 
“ every interruption is to be avoided as dangerous an 
objection so vague, as neither to require nor to admit a very 
distinct reply. Don George Juan, too, after a calculation of 
the absolute strength of the pieces of timber employed in the 
construction of a ship, very properly remarks, that the effect 
of arching must be attributed not to their want of strength, 
but to ‘‘ their play on each other." 
g. Mr, Seppings's Braces. 
It appears therefore to be sufficiently established, that the 
principle of employing oblique timbers is a good one, provided 
that it be so applied as to produce no practical inconvenience. 
We must next inquire whether Mr. Seppings has introduced 
it in a manner likely to be eflectual, and not liable to any 
