Abstract
THE memoir described below1 contains an account of experiments undertaken to test the author's theory, propounded some years ago, of the cause of the cleavage property in slates. Dr. Becker's theory, substantially the same as that put forward earlier by the Rev. O. Fisher, is that cleavage-planes are planes of maximum tangential strain, or in other words shear-planes. This is opposed to the theory of Sharpe (or, as we might say, of Sharpe and Sorby), which makes the cleavage-planes perpendicular1 to the maximum compression. The author has misunderstood1 Dr. Sorby's position, having apparently overlooked the earlier papers of that writer. The question whether1 heterogeneity in the rock is necessary for the production of cleavage seems to be beside the mark, since all rocks (other than glasses) are heterogeneous in this sense. Both Tyndall's wax and Dr. Becker's ceresin, being crystalline bodies, are heterogeneous, and their behaviour must depend on the orientation of the minute component crystals.
Article PDF
Rights and permissions
About this article
Cite this article
H., A. The Cleavage of Slates . Nature 72, 20 (1905). https://doi.org/10.1038/072020a0
Issue Date:
DOI: https://doi.org/10.1038/072020a0