If the two lowest tests in plain concrete and the two highest in concrete-steel had not been made, the average would be in favor of the plain concrete by nearly as much as Mr. Thompson’s average now favors the concrete-steel columns.  Further, if these four tests be eliminated, only three of the concrete-steel columns are higher than the plain concrete.  So much for the value of averages and the conclusions drawn therefrom.

It is idle to draw any conclusions from such juggling of figures, except that the addition of longitudinal steel rods is altogether problematical.  It may lessen the compressive strength of a concrete column.  Slender rods in such a column cannot be said to reinforce it, for the reason that careful tests have been recorded in which columns of concrete-steel were weaker than those of plain concrete.

In the averages of the Minneapolis tests Mr. Thompson has compared the results on two plain concrete columns with the average of tests on an indiscriminate lot of hooped and banded columns.  This method of boosting the average shows anything but “critical examination” on his part.

Mr. Thompson, on the subject of Mr. Withey’s tests, compares plain concrete of square cross-section with concrete-steel of octagonal section.  As stated before, this is not a proper comparison.  In a fragile material like concrete the corners spall off under a compressive load, and the square section will not show up as well as an octagonal or round one.

Mr. Thompson’s contention, regarding the Minneapolis tests, that the concrete outside of the hoops should not be considered, is ridiculous.  If longitudinal rods reinforce a concrete column, why is it necessary to imagine that a large part of the concrete must be assumed to be non-existent in order to make this reinforcement manifest?  An imaginary core could be assumed in a plain concrete column and any desired results could be obtained.  Furthermore, a properly hooped column does not enter into this discussion, as the proposition is that slender longitudinal rods do not reinforce a concrete column; if hoops are recognized, the column does not come under this proposition.

Further, the proposition in the writer’s fifteenth point does not say that the steel takes no part of the compression of a column.  Mr. Thompson’s laborious explanation of the fact that the steel receives a share of the load is needless.  There is no doubt that the steel receives a share of the load—­in fact, too great a share.  This is the secret of the weakness of a concrete column containing slender rods.  The concrete shrinks, the steel is put under initial compression, the load comes more heavily on the steel rods than on the concrete, and thus produces a most absurd element of construction—­a column of slender steel rods held laterally by a weak material—­concrete.  This is the secret of nearly all the great wrecks in reinforced concrete:  A building in Philadelphia, a reservoir in Madrid,