as not to find out that they were authorizing successive statements of the same quantity as inconsistent with each other as 2,000 and 5,000.
The next example is given by Dr. Lettsom, who, in his evidence before the Parliamentary Committee in 1802, calculated the small-pox deaths of Great Britain and Ireland before vaccination at 36,000 annually; by taking 3,000 as the annual mortality in London and multiplying by twelve, because the population was estimated to be twelve times as large. He first takes a number which is much too high, and then assumes that the mortality in the town, village, and country populations was the same as in overcrowded, filthy London! Small-pox was always present in London, while Sir Gilbert Blane tells us that in many parts of the country it was quite unknown for periods of twenty, thirty, or forty years. In 1782 Mr. Connah, a surgeon at Seaforcl, in Sussex, only knew of one small-pox death in eleven years among a population of 700. Cross, the historian of the Norwich epidemic in 1819, states that previous to 1805 small-pox was little known in this city of 40,000 inhabitants, and was for a time almost extinct; and yet this gross error of computing the small-pox mortality of the whole country from that of London (and computing it from wrong data) was not only accepted at the time, but has been repeated again and again down to the present day as an ascertained fact!
In a speech in Parliament in defence of vaccination, Sir Lyon Playfair gave 4,000 per million as the average London death-rate by small-pox before vaccination—a number nearly double that of the last twenty years of the century, which alone affords a fair comparison. But far more amazing is the statement by the late Dr. W. B. Carpenter, in a letter to the Spectator of April, 1881, that " a hundred years ago the small-pox mortality of London alone, with its then population of under a million, was often greater in a six months' epidemic than that of the twenty millions of England and "Wales now is in any whole
