The Reflections contained many surprising odds and ends of calculation. John Graunt computed that seven men out of every hundred in England live to the age of seventy; that only three women out of two hundred died in childbed and only one in labour; and that out of one hundred people, only one will be left alive at the age of 76 and none at the age of 80. He deduced from his calculations that the world was not more than 100,000 years old, and he drew, probably for the first time, that distinction in land values which has made, and continues to make, so loud a stir in our generation. For, in putting questions as to the amount of hay an acre that a meadow might bear, or the number of cattle which it might feed, he adds “of which particulars I quote the intrinsic value, for there is another value, merely accidental or extrinsic, consisting of the causes why a parcel of land lying for a good market may be worth double another parcel, though but of the same intrinsic goodness; which answers the question why lands in the North of England are worth but sixteen years’ purchase and those of the West above twenty-eight.” He aimed at classifying the vocations of men, with a word, by the way, against Doctors, who persuade “credulous and delicate people that their bodies are out of tune.” He thus raised a number of interesting problems for the speculation of thinking men, and there is little doubt that to the influence of his book was due a vital amendment in the Bills of Mortality. In 1728, the ages of the dead were included as well as the ailments from which they had died. The second of the three men was Sir William Petty, a man of a very different stamp. He was a speculator; he had a great love of money and a great love of land. He probably had a sense of humour, for, when challenged to fight a duel and having the privilege of choosing the place and the weapons, he selected a dark cellar and a carpenter’s axe. He certainly had the ambition to found a great family and leave to it a great inheritance, and in this he succeeded. He was the son of a Romsey tailor, and he left the house of Lansdowne. Petty wrote “An Essay on Arithmetic concerning the Growth of the City of London, with the Measures, Periods, Causes and Consequences thereof.” Petty estimated that in 1682 the population of London was 670,000, it having doubled itself within the preceding forty years. He was at a loss, however, to account for the increase. He could, he said, pick up some remarkable accident and declare it to be the cause, “as vulgar people make the cause of every man’s sickness to be, what he did last eat.” But Petty was not content with such a device, and preferred to attribute the swelling numbers to some natural and spontaneous advantage that men find by living in great societies.