No law has hitherto been discovered, by which a correct table of mortality could be constructed, but attempts have been made by De Moivre and others to obtain an approximation.

If, in conformity with the opinion now generally entertained, and in which I concur, we adopt the Carlisle Table of Mortality, as formed by Milne from the observations made by Dr. Heysham, as a nearer approximation to the actual duration of human life than any other table of mortality hitherto in use, it is remarkable that the following simple hypothesis should enable us to obtain the expectation of life almost identical with Milne's table for a long series of years up to the age of 60.