The number of Scientific Opinion for October 27 (page 457), contains a note by the Rev, Osmond Fisher, calling attention to a suggestion, with regard to the liquefaction of deeply buried rocks, made by him in a paper read before the Cambridge Philosophical Society in April, 1868, and since published in the Transactions of that Society. In a notice of this paper by him, in the Geological magazine for November, 1868, Mr. Fisher insists that deeply buried and intensely heated portions of rock, which, in accordance with the conclusions of Mr. Hopkins, are kept in a solid state by great pressure, may, by a diminution of pressure consequent upon movements of the earth's crust, assume a liquid condition, and thus give rise to lavas. This suggestion is however claimed by Mr. Scrope, in a communication to the same Magazine for December, 1868, as his own, and as having been put forward by him in both editions of his now classic work on Volcanos. This statement of Mr. Scrope was questioned by Mr. Fisher in the Geological magazine for January, 1869, and Mr. Scrope does not appear to have replied. In a paper in the same magazine for June, 1869, I have referred to this view as belonging to Mr. Scrope, and as also advocated by Mr. Fisher, who has availed himself of the republication of my paper in Scientific Opinion for October 20, to re-assert his claim to be the originator of this view, and to demand either of Mr. Scrope or myself some justification of our assertions.