"Will you decide a little argument which my
mate and I have been havingr ' said a carpenter
friend of mine as he and his mate came into the
ofi&ce the other morning. **We want to know
which is the stronger of two pitch pine beams
we have outside here. One is 9 inches by 6
inches, and the other 8 inches by 7 inches; and
both are to be used over openings of 12-feet
span. My mate thinks the 9 by 6 is the stronger
of the two, but I hold that the 8 by 7 will carry
more weight."

"I shall be very pleased to work it out for
you, and can tell you the result in about a min-
ute;" said I, **but if you have half an hour to
spare, I should prefer to show you how I arrive
at my figures, and thus enable you to make the
necessary calculations for yourselves whenever
you desire."

As work was not very pressing that morn-
ing, they readily agreed to take a lesson, and I
proceeded somewhat as follows:

A piece of wood 1 inch square placed on
bearings one foot apart, will break under a cer-
tain weight. This wieght varies with different
woods and with different specimens of the same
wood; but most authorities have agreed to re-

293



294 FBAMING

gard certain average weights as standards.
These averages were obtained from hundreds of
experiments, and are therefore fairly reliable.
The following table deals with a few woods only,
but is sufficient for our present purpose.
