equations. Certainly, the elastic theory gives a better guess in regard
to the location of the line of pressure than any guess made without its
use. The elastic theory was fully proved for arches by the remarkable
tests, made in 1897 by the Austrian Society of Engineers and Architects,
on full-sized arches of 70-ft. span, and the observed deflections and
lateral deformations agreed exactly with the figured deformation.

Tests on full-sized arches also showed that the deformations caused by
temperature changes agree with the elastic theory, but are not as great
for the 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. Considère, 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.