10 910 28 358 46 169
12 860 30 328 48 155
14 810 32 299 50 143
16 760 34 276 52 132
18 710 36 258 54 122
20 660 38 239 56 114
22 570 40 224 58 106
60 99

In tensional strains, the length of the beam does not affect the
strength; but in the beams submitted to compression, the length is a
most important element, and in the table given above, the safety
strains to which beams may be subjected, without crushing or bending,
has been given for lengths, varying from 6 to 60 diameters.


PRACTICAL RULES.

=Tensional Strain.=

Let T = whole tensional strain.
" S = strength per square inch.
" a = sectional area in inches.
Then we have T = Sa.

Now to find the necessary sectional area for resisting any strain, we
have the following general formula:

T
a = ---