arch, that it would "stand if the rods supporting the intrados of the
arch were keyed back to washers covering a sufficiently large area," by
inserting the words, "unless creeping pressures (such as those
encountered by the writer in his experiments) were exceeded."

The writer considers as very doubtful the formula for _D_{x}_, which is
the same as that for _W_{1}_, already discussed. The author's statement
that "additional back-fill will [under certain circumstances] lighten
the load on the structure," is considered subject to modification by
some such clause as the following, "the word 'lighten' here being
understood to mean the reduction to some extent of what would be the
total pressure due to the combined original and added back-fill,
provided no arch action occurred."

The writer is in entire agreement with the author as to the probability
that water is often "cut off absolutely from its source of pressure,"
with the attendant results described by the author (p. 378); and again,
that too little attention has been given to the bearing power of soil,
with the author's accompanying criticism.

The writer cannot see, however, where the author's experiments
demonstrate his statement "that pressure is transmitted laterally
through ground, most probably along or nearly parallel to the angles of
repose," or any of the conclusions drawn by him in the paragraph (p.
381), which contains this questionable statement. Again the writer is at
a loss as to how to interpret the statement that the author has found
that "better resistance" has been offered by "small open caissons sunk
to a depth of a few feet and cleaned out and filled with concrete" than
by "spreading the foundation over four or five times the equivalent
area." The writer agrees with the author in the majority of his