If we compare the number of deaths from Small Pox, which took place during the twenty-five years (from 1784 to 1798 inclusive) which immediately preceded Vaccination, amounting to 46,996, with the number which has taken place during the twenty-five years which have elapsed since its introduction (from 1799 to 1823 inclusive), amounting to 25,869, we shall find that an actual diminution has taken place of no fewer than 21,127, or nearly one half of the whole. It may, therefore, be confidently assumed, even upon this very simple calculation, that a number of lives equal to this diminution has been saved by Vaccination, within the bills of mortality alone. And as this diminution in the amount of mortality from Small Pox is going on in a progressive ratio, it is probable that the next twenty-five years will afford a yet more striking result. If we extend this calculation to the whole of Great Britain and Ireland, assuming that the ratio in the diminution of deaths has been the same over the united kingdom as within the London bills of mortality—(and there are various good reasons for believing that it has been greater)—we cannot but be struck with the immense saving of human life which has already taken place. Sir Gilbert Blane and Dr. Letsom separately calculated the annual loss of lives from Small Pox, in Great Britain and Ireland, during the last thirty years of the eighteenth century.—One of these eminent physicians estimated them at 34,260, and the other at 36,000 (Moore’s History of Small Pox, p. 300): For our present purpose, we will take a medium number, as being probably nearest to the truth. Assuming then, that the number of deaths from Small Pox, in the United Kingdom, during each of the twenty-five years which preceded the introduction of Vaccination, amounted to 35,000, the amount, during the whole of that period, must have been 875,000. But if the diminution on the whole of this number has been equal to that which is proved to have taken place within the London bills of mortality, during the last twenty-five years, it must have been reduced to 481,644 only, and an actual saving of the lives of 393,356 individuals must have been accomplished.