a a Se: 
and Strength of Materials. 235 
square were broken by 525 pounds at a 
medium.” 
«Six bars were cut $d through, and the cut 
filled with a wedge of hard wood stuck in 
with a little force; these were broke with 
551. Six bars were cut + through, andthe 
cut was filled in the same manner; they 
broke with 542. Six bars were cut iths 
through ; they broke with 530. A batten 
cut 3ths through, and loaded till nearly 
broken, was unloaded, and the wedge taken 
out of the cut. A thicker wedge was put in 
tight so as to make the batten straight again, 
by filling up the space left by the compression 
of the wood; this batten broke with 577 
pounds.” 
* From this,” Dr, R. remarks, “itis plain 
that more than 3ds of the thickness, perhaps 
nearly iths, contributed nothing to the 
strength.” 
12. It appears from these experiments, that 
in the fracture of willow, a considerable com- 
pression takes place, and it doubtless would 
do to a certain degree in that of every other 
body.* 
We know too that extension of the remain- 
* Mr. Barlow has shewn thatit is the case in all the 
different descriptions of timber. 
