320 
Df\ Young’s Remarks on the 
gained by the further addition of oblique braces : and it will 
appear that if the braces were fixed to the outermost planks 
of the series only, they would have no manner of effect either 
on the strength or on the stiffness, whatever might be their 
direction ; but if they W’ere sufficiently fastened throughout 
their extent to each plank with which they come into contact, 
they would add both to the strength and to the stiffness, very 
nearly in the same degree as if they were fixed in the direc- 
tion of the planks, at a distance from each other equal to their 
shortest actual distance, so as to constitute as many ribs as 
there are braces in a transverse line (fig. 6).^ Hence, al- 
though there is obviously no economy in such an employment 
of oblique braces, yet it is by no means true that oblique 
braces are incapable of adding to the strength of a structure 
composed of pieces arranged at right angles ; the assertion 
might however be very nearly correct in circumstances ap- 
proaching to those of one of the experiments wdiich have been 
exhibited for the purpose of illustrating the utility of such 
braces. On the other hand, the advantage of employing ob- 
lique braces must depend in great measure on the degree in 
which the angular position of the structure w'ould be suscep- 
tible of variation without them ; since, wken properly fastened, 
they must universally tend to preserve the form unaltered, 
* The extension and compression of the whole fabric being supposed equal, the 
diagonal braces will undergo no change of length, and therefore will not assist in the 
resistance, if only attached at their extremities. But In reality, although the exten- 
sion and compression may be very nearly equal in the first instant of the change of 
form, the extension will always be much greater after a certain time, from the imper- 
fection of the fastenings, which will allow the parts to separate, while their own re- 
sistance prevents their compression in a material degree : so that oblique braces, how- 
ever fixed, must in this respect add considerably to the strength. 
