D/‘. Young’s Remarks on the 
316 
they are incomparably weaker, with respect to any transverse 
force, than when the intermediate pieces are in an oblique 
direction, so as to constitute a frame, which can only be bent 
as a whole. But it cannot for a moment be imagined, that 
the planks of a ship are connected with the timbers in as loose 
a manner as these transverse braces, which will scarcely sup- 
port their own weight for the purpose of the experiment; and in 
fact the comparison would have required, that the whole space 
included by the parallelogram should be filled up in each case 
by similar braces, or at least that the two planks should have 
been firmly united at the loose end to the transverse braces 
(fig. 3); and it is demonstrable that in this case the same 
weight would have broken the pins, as if one of the planks 
had been oblique, or as if the planks had remained parallel, 
and had been connected by oblique pieces. 
Such a result would, however, be far from proving the in- 
utility of the addition of oblique braces to a rectangular frame: 
for the kind of strength, required for any particular purpose, 
is not always determined by the magnitude of the force which 
would be capable of breaking the substances concerned, al- 
though the power of resisting such a force is properly called 
strength, in the most limited sense of the term : but there are 
many occasions on which stiffness or inflexibility is of still 
greater consequence than strength, and others again on which 
flexibility is of material advantage. A coach spring, consist- 
ing of ten equal plates, would be rendered ten times as strong, 
if it were united into one mass, and at the same time a hun- 
dred times as stiff, bending only one hundredth of an inch 
with the same weight that would bend it a whole inch in its 
usual state, although nothing would be gained by the union 
