design warned him against shallow stringers on that account,
and told him that such things had happened.

Is it certain that structural steel design is on such a sound basis
after all? Recent experiences seem to cast some doubt on it, and we may
yet discover that we have escaped trouble, especially in buildings,
because we almost invariably provide for loads much greater than are
ever actually applied, and not because our knowledge and practice are
especially exact.

_Point 8._--The writer believes that this point is well taken, as to a
great deal of current practice; but, if the author's ideas are carried
out, reinforced concrete will be limited to a narrow field of
usefulness, because of weight and cost. With attached web members, the
writer believes that steel can be concentrated in heavy members in a way
that is not safe with plain bars, and that, in this way, much greater
latitude of design may be safely allowed.

_Point 9._--The writer is largely in accord with the author's ideas on
the subject of T-beams, but thinks he must have overlooked a very
careful and able analysis of this kind of member, made by A.L. Johnson,
M. Am. Soc. C. E., a number of years ago. While too much of the floor
slab is still counted on for flange duty, it seems to the writer that,
within the last few years, practice has greatly improved in this
respect.

_Point 10._--The author's statement regarding the beam and slab formulas
in common use is well grounded. The modulus of elasticity of concrete is
so variable that any formulas containing it and pretending to determine
the stress in the concrete are unreliable, but the author's proposed
method is equally so. We can determine by experiment limiting
percentages of steel which a concrete of given quality can safely carry
as reinforcement, and then use empirical formulas based on the stress in
the steel and an assumed percentage of its depth in the concrete as a
lever arm with more ease and just as much accuracy. The common methods
result in designs which are safe enough, but they pretend to determine
the stress in concrete; the writer does not believe that that is
possible within 30% of the truth, and can see no profit in making
laborious calculations leading to such unreliable results.

_Point 11._--The writer has never designed a reinforced concrete
chimney, but if he ever has to do so, he will surely not use any formula
that is dependent on the modulus of elasticity of concrete.

_