Page:Life of Sir William Petty 1623 – 1687.djvu/206

 little book—it occupies barely 100 pages—was the first serious attempt to classify vital statistics and define the limits of a science respecting them. It met with an extraordinary success, and at the Restoration the King ordered Graunt's name to be enrolled amongst the members of the Royal Society, adding that, if there were any more such tradesmen in his City of London, he desired they also should be enrolled immediately. In France Colbert is believed to have been encouraged by it to provide for the first regular register of births and deaths.

Towards the end of his career, Sir William wrote some 'Observations on the Dublin Bills of Mortality' in imitation of those which Graunt had published many years before. The publisher protested against the brevity of the manuscript sent him, which in size hardly exceeded a pamphlet. At his request Sir William added a postscript, but wrote at the same time: 'Whereas you complain that these observations make no sufficient bulk, I could assure you that I wish the bulk of all books were less.' 'The observations upon the London Bills of Mortality,' the book opens by saying, 'have been a new light to the world, and the like observations upon those of Dublin may serve as snuffers to make the same candle burn clearer,' The collection of statistics naturally led Petty and Graunt to attempt to deduce some general laws from them, and thus the whole field of public economy, or, as Sir William Petty generally termed it, 'political arithmetick,' was opened up to their investigations.

Observation, it has been said, is the one eye of political economy, and comparison the other. Sir William was one of the first to grasp the fact, and was singularly successful in seeing through both eyes if, at least, he is to be judged by the knowledge of the times—in such a case the only legitimate standard of comparison. Political economy, in the modern