ding remarks,
wherein he ascribes to arch action the results which he believes would
be observed if "a long shaft be withdrawn vertically from moulding
sand." These phenomena would be due rather to capillary action and the
resulting cohesion.

Naturally, the writer doubts the author's conclusions as to the pressure
at the top of large square caisson shafts when he states that "the
pressure at the top * * * will * * * increase proportionately to the
depth." Again, the author is apparently not conversant with experiments
made by the Dock Department of New York City, concerning piles driven in
the Hudson River silt, which showed that a single heavily loaded pile
carried downward with it other unloaded piles, driven considerable
distances away, showing that it was not the pile which lacked in
resistance, as much as the surrounding earth.

In conclusion, the writer heartily concurs with the statement that "too
much has been taken for granted in connection with earth pressures and
resistance," and he is sorry to be forced to add that he believes the
author to be open to the criticism which he himself suggests, that "both
in experimenting and observing, the engineer [and in this case the
author] will frequently find what is being looked for or expected and
will fail to see the obvious alternative."

FRANCIS L. PRUYN, M. AM. SOC. C. E. (by letter).--Mr. Meem
should be congratulated, both in regard to the highly interesting
theories which he advances on the subject of sand pressures--the
pressures of subaqueous material--and on his interesting experiments in
connection therewith.

The experiment in which the plunger on the hydraulic ram is immersed in
sand and covered with water does not seem to be conclusive. By this
experiment the author attempts to demonstrate that the pressure of the
water transmitted through the sand is only about 40% as great as when
the sand is not there. The travel of ground-water through the earth is
at times very slow, and occasionally only at the rate of from 2 to 3 ft.
per hour. In the writer's opinion, Mr. Meem's experiment did not cover
sufficient time during which the pressure was maintained at any given
point. It is quite probable that it may take 15 or 20 min. for the full
pressure to be transmitted through the sand to the bottom of the
plunger, and it is hoped, therefore, that he will make further
experiments lasting long enough to demonstrate this point.

In regard to the question of s