can anyone * * * doubt that the top timbers are stressed more heavily than those at the bottom,” is emphatically doubted and earnestly denied by the writer.  Furthermore, “the assumption” made by the author as to “the tendency of the material to slide” so as to cause it “to wedge * * * between the face of the sheeting * * * and some plane between the sheeting and the plane of repose,” is considered as absolutely unwarranted, and consequently the whole conclusion is believed to be unjustified.  Nor is the author’s assumption (line 5, p. 361), that “the thrust * * * is measured by its weight divided by the tangent of the * * * angle of repose” at all obvious.

The author presents some very interesting photographs showing the natural surface slopes of various materials; but it is interesting to note that he describes these slopes as having been produced by the “continual slipping down of particles.”  The vast difference between angles of repose produced in this manner by the rolling friction of particles and the internal angles of friction, which must be used in all earth-pressure investigations, has been repeatedly called to the attention of engineers by the writer.[H]

The writer’s experiments are entirely in accord with those of the author in which the latter claims to demonstrate that “earth and water pressures act independently of each other,” and the writer is much delighted that his own experiments have been thus confirmed.

In Experiment No. 3, the query is naturally suggested:  “What would have been the result if the nuts and washers had first been tightened and water then added?” Although the writer has not tried the experiment, he is rather inclined to the idea that the arch would have collapsed.  With regard to Experiment No. 5, there is to be noted an interesting possibility of its application to the theoretical discussion of masonry dams, in which films of water are assumed to exist beneath the structure or in crevices or cracks of capillary dimensions.  The writer has always considered the assumptions made by many designing engineers as unnecessarily conservative.  In regard to the author’s conclusions from Experiment No. 6, it should be noted that no friction can exist between particles of sand and surrounding water unless there is a tendency of the latter to move; and that water in motion does not exert pressures equal to those produced when in a static condition, the reduction being proportional to the velocity of flow.

The author’s conclusion (p. 371), that “pressure will cause the quicksand to set up hydraulic action,” does not seem to have been demonstrated by his experiments, but to be only his theory.  In this instance, the results of the writer’s experiments are contrary to the author’s theory and conclusion.

The writer will heartily add his protest to that of the author “against considering semi-aqueous masses, such as soupy sands, soft concrete, etc., as exerting hydrostatic pressure due to their weight in bulk, instead of to the specific gravity of the basic liquid.”  Again, similarly hearty concurrence is given to the author’s statement: