Journal . In a true fluid there would be, at the same point, no differencebetween the intensity of pressure and the intensity of resistance,to attain which condition of perfect fluidity both k and a mustbecome zero. In one important point Mr. Ackermanns inquiry had differedfrom his own in that the latter was directed towards the deter-mination of the pressures and resistances in undisturbed clay— 174 DELAYED DISCUSSION ON that being the problem to which he had had to find a illustrate the point he might allude to a very simple littleexperiment which he had made before undertaking h
Journal . In a true fluid there would be, at the same point, no differencebetween the intensity of pressure and the intensity of resistance,to attain which condition of perfect fluidity both k and a mustbecome zero. In one important point Mr. Ackermanns inquiry had differedfrom his own in that the latter was directed towards the deter-mination of the pressures and resistances in undisturbed clay— 174 DELAYED DISCUSSION ON that being the problem to which he had had to find a illustrate the point he might allude to a very simple littleexperiment which he had made before undertaking his publishedinvestigation. He had taken a small cube of common soap, asillustrated below :—. Holding this in one hand between finger and thumb appliedrespectively to the two horizontal surfaces ABCD and EFGH, hehad placed the finger and thumb of the other hand on the twovertical and opposing faces BCGF and ADHE ; then exertingpressure with one hand upon the horizontal surfaces, he hadnoted the slight corresponding outward movement of the verticalfaces felt by the finger and thumb of the other hand. Thisslight movement appeared to depend upon the elasticity of thematerial which, so far as he could judge, returned upon release ofthe pressure to its original form. The next step which he took was to cut the cube through witha knife on the diagonal plane BCHE—approximately the plane ofmaximum shear. Replacing the fingers as before, he noted thegreat increase in the lateral pressure which had followed uponthe destruction of the initial shearing resistance along the planeBCHE. The shearing resistances of undisturbed material undervarying conditions of normal pressure, and the dete
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Keywords: ., bookcentury1800, bookdecade186, bookpublisherlondon, bookyear1861
