266 On the Transverse Strain, 
With this view I took a piece of iron wire, 
7 feet long, and weighing 2 dwts. 17 grs. 
and hanging a two pound weight to it to ren- 
der it perfectly straight, noted its extensions 
in parts of an inch, which are as follow: 
With 10]bs. it stretched .07 
1 ee Ee | OS 16 
CN ene Pee eee .26. It returned, 
when the 30ib was taken off, to 03, and broke 
with 35lbs, 
Another similar wire stretched .26 inch 
with 30ibs, and broke with 35ibs. This wire, 
like the former, weighed 2 dwts. 17 grs. 
I then compared the strength of the iron I 
used with that of the wire, and found the 
former about 319 times as strong as the lat- 
ter. And as not more than 3 inches of the 
iron was subjected to uninterrupted extension, 
the error, from the dilatation of the iron, 
could not, in any of the experiments we have 
given, have influenced the deflections as 
much as ;2., part of an inch, and in the two 
last must have affected them less than ;2,. 
The mode of calculation we used, was to 
find the effect of a weight equal to + the 
greatest we made use of, upon the end of a 
lever, one arm of which was = half the greatest 
distance between the props, and the other 
arm 3ds of an inch = the distance of the cen- 
