Page:William Petty - Economic Writings (1899) vol 1.djvu/88

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Almost all of Graunt's "Observations" and a large portion of Petty's "Essays" are based on the London bills of mortality. Some knowledge of the history and character of the bills is therefore necessary to an appreciation of those writings. Accordingly the gradual elaboration of the Parish Clerk's bills from crude weekly returns of the progress of the plague, through a long series of changes, to the form finally superseded by the Registrar-General's bills in 1840, is here traced as far as the year 1686, the last year of whose bills Petty made use, and an attempt is made to estimate the accuracy of the seventeenth century bills in several particulars.

So far as is known, no set of the London bills of mortality before 1658 escaped the great fire of September, 1666 and there is, in consequence, some doubt as to the time at which they originated. Graunt's assertion that the bills first began in the year 1592 accords with the official statement put forth, after the Plague of 1665 and before the Fire, by John Bell, clerk to the Company of Parish Clerks, to rectify "the many and gross mistakes which have been imposed upon the World, by divers Ignorant Scriblers about the weekly Accompts of former Visitations ." Bell says that he could find in the Parish Clerks' Hall no record of more antiquity than 21 December, 1592; the bills, therefore, must have begun at that date. In 1595, he continues, the plague ceased, and on the 18th December of that year the bills were accordingly discontinued