272 On the Transverse Strain, 
In Dantzic Fir, 
From Ist experiment, as 2324 to 250 
Qn ois idcevieeca cae 31 227E to 250* 
Mean ratio 23 to 25 
In Quebec Cak, 
From Ist experiment, as 210 to 242% 
DAG evden tunvecivecee SENS UO O4e 
Oidsts.d. Socsweres 252! to 2922 
— -_——_— 
Meanratio 27to3l 
33. The situation of the neutral line ina 
joist being known, we shall be enabled to 
find from that its position in beams of other 
forms; for since in all moderate strains the 
extensions and compressions are nearly as the 
forces, we have (from Cor. 2, Art. 20) see- 
tion of tension X g : section compression 
x g ::¢: 8, a constant ratio—And hence 
this general rule— 
Divide the surface of fracture into two 
such parts that the section of tension, multi- 
plied by the distance of its centre of gravity 
* Mr. Barlow found that the area of tension to that of 
compression in rectangular fir beams was nearly as 3 to 5, 
which is a considerably greater compression than that given 
above; but our experiments were made during moderate 
strains, and his at the time of fracture. Admitting both to 
be correct, it possibly may be accounted for by the ten- 
dency that soft woods have to cripple when over com- 
pressed. 
and 
