In a paper “On the Height of the Land and the Depth of the Ocean,” read to the Society on 19th December 1887, and published in the Scottish Geographical Magazine, vol. iv. pp. 1–41, Dr John Murray gives a very detailed estimate of the volumes of oceanic hollows and continental protuberances. I have recently had recourse to Dr Murray's calculations in order to determine the position of the contour-line which should separate the portions of the solid earth above the general level of the surface from those below that level. The results of this determination were published in the Scottish Geographical Magazine, vol. vi. pp. 182–187; but since then the theoretical importance of the particular contour-line in question has induced me to give further consideration to the subject.