employment of Oblique Riders, 325 
material objections. He places, on the sides of a 74 ship, 
several series of oblique braces, principally between the ports, 
in the place of the internal planking, making an angle of about 
24,° with the decks ; consisting of planks four inches thick, and 
about 1 1 wide, coaked and bolted to the timbers, and abutting 
against upright pieces similarly fastened. Now it follows, 
from what has already been stated, that these pieces have 
about four fifths as mucli effect in cooperating with the 
neighbouring parts, which act horizontally, as if they had been 
placed in the same situation with them, even on the supposi- 
tion that the relative angular situation of the pieces is unalter- 
ably fixed : but for preventing the alteration of this situation, 
there is no doubt of their being very advantageously arranged, 
so far as their strength is sufficient ; and the existence of a 
tendency to such an alteration, in a very material degree, 
appears to be altogether indisputable. Below the gun deck, 
the oblique timbers are considerably stronger, altliough they 
act under circumstances somewhat less favourable. 
If, however, the resistance of a part of a structure is very 
immediately directed against a certain force, without an ade- 
quate cooperation from other parts of that structure, and if, 
being abandoned by those parts, it is exposed to a strain which 
it is too W’eak to withstand, it is obvious that it must inevitably 
be the first to give w'ay, and must leave the rest of the fabric 
more exposed to be overpowered by such a force, than before 
its introduction. We must therefore inquire, how far it is 
possible that Mr. Seppings's braces should be so abandoned. 
Now' supposing a 74 gun ship to arch two feet, and one half 
of the change to depend on the sliding of the planks over 
each other, which will be allow^ed, by those who doubt the utility 
U u 
MDCCCXIV. 
