IN Prof. Wyville Thomson's work â The Depths of the Seaâ there appears to me a curious discrepancy between two statements of the specific gravity of the sea, to which it may be useful to direct general attention. At p. 505, Mr. W. L. Carpenter states that the average specific gravity of surface-water, at a sufficient distance from land to be unaffected by local disturbances, was 1·02779, At p. 513, Dr. Frankland gives the specific gravity of four samples of surface-water, the mean of which is only 1·0267, even less than the minimum value as given by Mr. Carpenter. Both results are said to be for temperature 60° F. I should have expected Dr. Frankland's determination to have been the higher, from possible loss by evaporation. The difference may probably be due to want of identity of indication between the instruments used. From whatever cause it may arise, the difference is so considerable, as to leave no doubt whatever that it ought to be accounted for in some way ; and the error wherever it lies fully exposed.