the United
States appears to bear out the fact very clearly that longitudinal steel
bars embedded in concrete increase the strength of the column, and,
further, to confirm the theory by which the strength of the combination
of steel and concrete may be computed and is computed in practice.

Tests of large columns have been made at the Watertown Arsenal, the
Massachusetts Institute of Technology, the University of Illinois, by
the City of Minneapolis, and at the University of Wisconsin. The results
of these various tests were recently summarized by the writer in a paper
presented at the January, 1910, meeting of the National Association of
Cement Users[O]. Reference may be made to this paper for fuller
particulars, but the averages of the tests of each series are worth
repeating here.

In comparing the averages of reinforced columns, specimens with spiral
or other hooping designed to increase the strength, or with horizontal
reinforcement placed so closely together as to prevent proper placing of
the concrete, are omitted. For the Watertown Arsenal tests the averages
given are made up from fair representative tests on selected proportions
of concrete, given in detail in the paper referred to, while in other
cases all the corresponding specimens of the two types are averaged. The
results are given in Table 1.

The comparison of these tests must be made, of course, independently in
each series, because the materials and proportions of the concrete and
the amounts of reinforcement are different in the different series. The
averages are given simply to bring out the point, very definitely and
distinctly, that longitudinally reinforced columns are stronger than
columns of plain concrete.

A more careful analysis of the tests shows that the reinforced columns
are not only stronger, but that the increase in strength due to the
reinforcement averages greater than the ordinary theory, using a ratio
of elasticity of 15, would predicate.

Certain of the results given are diametrically opposed to Mr. Godfrey's
conclusions from the same sets of tests. Reference is made by him, for
example (page 69), to a plain column tested at the University of
Illinois, which crushed at 2,001 lb. per sq. in., while a reinforced
column of similar size crushed at 1,557 lb. per sq. in.,[P] and the
author suggests that "This is not an isolated case, but appears to be
the rule." Examination of this series of tests shows that it is somewhat
more err