Journal . nvestigation undertaken by Experiments so carefully carried out and accu-rately recorded could not fail to be useful to future experi-mentalists. That portion of the inquiry which related to the pressure offluidity had seemed to him the most interesting. His ownwork had not led him to conclude that, under any degree of pres-sure, clay would act as a perfect fluid, though clay containing alarge percentage of water might approximate to the fluid con-dition. A perfect fluid possessed no capacity to resist internalshear, and this was not, in his view, true of clay under any
Journal . nvestigation undertaken by Experiments so carefully carried out and accu-rately recorded could not fail to be useful to future experi-mentalists. That portion of the inquiry which related to the pressure offluidity had seemed to him the most interesting. His ownwork had not led him to conclude that, under any degree of pres-sure, clay would act as a perfect fluid, though clay containing alarge percentage of water might approximate to the fluid con-dition. A perfect fluid possessed no capacity to resist internalshear, and this was not, in his view, true of clay under anyconditions. He had shown that, under a head h the intensity ofactive horizontal pressure exerted by clay (of weight w) was— / a\ (ir a wh tan2 2k tan \4 2/ \4 2 and that the maximum intensity of resistance to horizontal move-ment at the same depth was— , * awh tan2 - + -v 4 ^ 2 r- 2k tan 1 - + - In these equations the values of k and a were those given in ashear diagram of the form indicated below :—. 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 :—
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Keywords: ., bookcentury1800, bookdecade186, bookpublisherlondon, bookyear1861
