of the steel;
_As_ = the area of the steel;
and _f_ = the allowable stress per square inch in the steel.

The difference, however, is very slight, the results from the two
formulas being proportional to the two factors, 83-1/3 and 85 or 86.
This formula gives the area of steel required for the moment. The
percentage of steel to be used can easily be obtained from the allowable
stresses in the concrete and the steel, and the dimensions of the beam
can be obtained in the simplest manner. This formula is used with great
success by one of the largest firms manufacturing reinforcing materials
and designing concrete structures. It is well-known to the Profession,
and the reason for using any other method, involving the Greek alphabet
and many assumptions, is unknown to the writer. The only thing to
assume--if it can be called assuming when there are so many tests to
locate it--is the position of the neutral axis. A slight difference in
this assumption affects the resulting design very little, and is
inappreciable, from a practical point of view. It can be safely said
that the neutral axis is at, or a little above, the center of the beam.

Further, it would seem that the criticism to the effect that the initial
stress in the concrete is neglected is devoid of weight. As far as the
designer is concerned, the initial stress is allowed for. The values for
the stresses used in design are obtained from tests on blocks of
concrete which have gone through the process of setting. Whatever
initial stress exists in concrete due to this process of setting exists
also in these blocks when they are tested. The value of the breaking
load on concrete given by any outside measuring device used in these
tests, is the value of that stress over and above this initial stress.
It is this value with which we work. It would seem that, if the initial
stress is neglected in arriving at a safe working load, it would be safe
to neglect it in the formula for design.

EDWIN THACHER, M. AM. SOC. C. E. (by letter).--The writer will discuss
this paper under the several "points" mentioned by the author.

_First Point._--At the point where the first rod is bent up, the stress
in this rod runs out. The other rods are sufficient to take the
horizontal stress, and the bent-up portion provides only for the
vertical and diagonal shearing stresses in the concrete.

_Second Point._--The remarks on the first point are also applicable to
the second one. Ro