Apropos of the plague—I do not know whether the following curious coincidence has been noticed. In that admirable work, John Graunt's “Natural and Political Observations upon the Bills of Mortality” (second edition, London, 1662), which is probably the earliest treatise on vital statistics, I find the following statement (p. 31):—“There have been in London, within this age, four times of great mortality, that is to say, the years 1592 and 1593, 1603, 1625, and 1636.” He shows that large numbers died of the plague in each of these years. Now, if we take the solar period to be 10(1/2 years, nearly in accordance with Dr. Lamont's and Mr. J. A. Broun's estimates, we get the subjoined table, which sufficiently explains itself.