Page:William Petty - Economic Writings (1899) vol 1.djvu/85

Rh of another, so in the Country they are seldom not more than so... which shows that the opener and freer Airs are most subject to the good and bad Impressions." This is an attempt to explain by physical conditions the wide range in the observed country death rate which is really due to the narrowness of the field—a single market town—under investigation. It is, perhaps, the gravest statistical mistake that can be charged against Graunt. And when we remember that he was a statistical pioneer, blazing his way through a trackless forest, we must confess surprise that his faults are so few and his merits so many. He had not enjoyed the academic training of most of his associates in the Royal Society, but he was permeated with the spirit of that new philosophy which bade curiosity turn for satisfaction rather to observation than to speculation. His book, with all its faults, deserves a place among the penetrating and fearless treatises which, marred though they were by much now known to be absurd, still contributed to render even the early years of the Royal Society illustrious.

Graunt's influence upon later statistical writers can be traced with remarkable distinctness. Petty is the first to acknowledge as he was the first to feel it; but his obligation is of that vital sort which no series of quotations can sufficiently express. How largely his best work depends upon Graunt can be appreciated only by reading in connection with Graunt's "Observations" the second volume of Petty's Economic Writings. Upon Halley's "Estimate of the Degrees of Mortality of Mankind" (1693) Graunt's influence is not quite so obvious. But anyone who has read, as to some extent I have, the scattered letters of Petty, Southwell, Williamson, Pett, and Justel, all members of the Royal Society and friends of Petty, and all but Justel acquainted with Graunt, cannot fail to see how, as a result of Graunt's and Petty's efforts, the air surrounding Halley was full of political arithmetic. He turned his great abilities as it were casually and but for a few days to that subject; but he seized at once upon Graunt's most striking discovery, the regularity of death, and utilized it for the first suggestion of life insurance. Of Gregory King and Charles Davenant it is not necessary to speak. They belong rather to Petty's school than to Graunt's. The next link in the chain of Graunt's influence is the Rev. William Derham (1657-1735). As Boyle lecturer in 1711-12 Derham, having the honour to be a member of the Royal Society as well as a divine, was minded to try what he could do toward the improvement of