The author’s logic is believed to be entirely faulty in many cases because he repeatedly makes assumptions which are not in accordance with demonstrated fact, and finally sums up the results by the statement:  “It is conceded” (line 2, p. 357, for example), when the writer, for one, has not even conceded the accuracy of the assumptions.  For instance, the author’s well-known theory that pressures against retaining walls are a maximum at the top and decrease to zero at the bottom, is in absolute contradiction to the results of experiments conducted on a large scale by the writer on the new reinforced concrete retaining wall near the St. George Ferry, on Staten Island, New York City, which will soon be published, and in which the usual law of increase of lateral pressure with depth is believed to be demonstrated beyond question.  It must be conceded that a considerable arch action (so-called) actually exists in many cases; but it should be equally conceded by the advocates of the existence of such action that changes in humidity, due to moving water, vibration, and appreciable viscosity, etc., will invariably destroy this action in time.  In consequence, the author’s reasoning in regard to the pressures against the faces of retaining walls is believed to be open to grave question as to accuracy of assumption, method, and conclusion.

The author is correct in so far as he assumes that “the character of the stresses due to the thrust of the material will” not “change if bracing should be substituted for the material in the area” designated by him, etc., provided he makes the further assumption that absolutely no motion, however infinitesimal, has taken place meantime; but, unless such motion has actually taken place, no arch action can have developed.  An arch thrust can result only with true arch action, that is, with stable abutments, and the mass stressed wholly in compression, with corresponding shortening of the arch line.  The arch thrust must be proportional to the elastic deformation (shortening) of the arch line.  If any such arch as is shown in Fig. 5 is assumed to carry the whole of the weight of material above it, that assumed arch must relieve all the assumed arches below.  Therefore each of the assumed arches can carry nothing more than its own mass.  Otherwise the resulting thrust would increase with the depth, which is opposed to the author’s theory.

Turning again to the condition that each arch can carry only its own weight:  if these arches are assumed of thicknesses proportional to the distance upward from the bottom of the wall, they will be similar figures, and it is easily demonstrated that the thrust will then be uniform in amount throughout the whole height of the wall, except, perhaps, at the very top.  This condition is contrary to the author’s ideas and also to the facts as demonstrated by the writer’s experiment on the 40-ft. retaining wall at St. George.  Consequently, the author’s statement:  “nor