e whole mass of the arch as is commonly assumed. The elastic
theory enables one to calculate arches much more quickly than any
graphical or guess method yet proposed.

Hooped columns are a patented construction which no one has the right to
use without license or instructions from M. Considere, who clearly
states that his formulas are correct only for rich concrete and for
proper percentages of helical and longitudinal reinforcement, which
latter must have a small spacing, in order to prevent the deformation of
the core between the hoops. With these limitations his formulas are
correct.

Mr. Godfrey brings up some erratic column tests, and seems to have no
confidence in reinforced concrete columns. The majority of column tests,
however, show an increase of strength by longitudinal reinforcement. In
good concrete the longitudinal reinforcement may not be very effective
or very economical, but it safeguards the strength in poorly made
concrete, and is absolutely necessary on account of the bending stresses
set up in such columns, due to the monolithic character of reinforced
concrete work.

Mr. Godfrey does not seem to be familiar with the tests made by good
authorities on square slabs of reinforced concrete and of cast iron,
which latter material is also deficient in tensile strength. These tests
prove quite conclusively that the maximum bending moment per linear foot
may be calculated by the formulas, (_w_ _l^{2}_)/32 or (_w_ _l^{2}_)/20,
according to the degree of fixture of the slabs at the four sides.
Inasmuch as fixed ends are rarely obtained in practice, the formula,
(_w_ _l^{2}_)/24, is generally adopted, and the writer cannot see any
reason to confuse the subject by the introduction of a new method of
calculation.

WALTER W. CLIFFORD, JUN. AM. SOC. C. E. (by letter).--Some of Mr.
Godfrey's criticisms of reinforced concrete practice do not seem to be
well taken, and the writer begs to call attention to a few points which
seem to be weak. In Fig. 1, the author objects to the use of diagonal
bars for the reason that, if the diagonal reinforcement is stressed to
the allowable limit, these bars bring the bearing on the concrete, at
the point where the diagonal joins the longitudinal reinforcement, above
a safe value. The concrete at the point of juncture must give, to some
extent, and this would distribute the bearing over a considerable length
of rod. In some forms of patented reinforcement an additional safegu