and Strength of Materials 259 
the tabular deflections as integers, since the 
result will be the same, we shall have— 
Tn the first, 
60% : 19 :: 240% : (83)’= 
a Log. 76 a 1.8808136 — 98 
Log. 83 1.9190781 
In the second, 
90: 20:: 270:(53)"= 60..°.v 
— 1.03. 
95. And taking the mean, we have 
pha mS — .97— ultimate mean value of - 
19 x 240 
Za —76. Whencev 
43 Log. 60__1.7781512 
Log. 53 1.7242759 
vy. A number which so nearly approaches to 
unity, the index of perfect elasticity, that it 
seems unnecessary to assume any other Jaw. 
COMPRESSION. 
26. The next subject of our inquiry is 
compression ; or the contractions which the 
fibres of a piece of timber would sustain by 
forces applied in the direction of their length. 
And as this snbject does not appear to have 
been much attended to by others, we trust it 
will plead our excuse if we give a detail of a 
greater number of experiments, than we 
otherwise should do of our own. 
What we have done in this matter was in 
pursuance of a similar idea to that we used in 
our last, only with this exception, that there 
we employed the iron to prevent compression 
