But the truly important result from these statements consists in the clear, undeniable, and great diminution of it since the introduction of Vaccination. It appears, that in the last fifteen years, the mortality from Small Pox, in the bills of mortality, has not been much more than one-half of what it was in the two like series of years in the middle and latter end of the last century. Nor does this comprise the whole benefit derived from this discovery in the metropolis; for, besides that the sixth part of it lies without the bills, it was found, in levying the tax on burials for the last six months of 1794, that the number of unregistered deaths, chiefly those of dissenters, amounted in that half year to 3148; and the reporter of the parliamentary enumeration thinks that, as besides these there were undiscovered interments, the unregistered deaths may be computed at one-third of the total mortality, that is, about 7000. (_See Abstract of the Parish Registers, 1811, printed by authority of Parliament, page 200._) Assuming, therefore, that Vaccination had not been practised the last fifteen years, and that the mortality from Small Pox, within the bills, had in that time, that is, from 1804 to 1818, been the same as from 1784 to 1798, that is, 27,569 in place of 14,716; and assuming that there has been the same proportional diminution of deaths in the districts without the bills, and among the unregistered subjects, the account of lives saved in this metropolis by Vaccination in the fifteen years, will stand as follows:— Within the bills of mortality 12,853 Without the bills of mortality 2,570 Unregistered cases 7,711 ------ Total 23,134 The first of these numbers is found by subtracting the amount of deaths by Small Pox, in the bills of mortality, during the practice of Vaccination, from the amount of them, during the same number of years, immediately before the discovery of Vaccination. The second number is found by dividing the first by 5. The population of the metropolis without the bills is stated at one-sixth of the whole, which is evidently one-fifth of that within the bills. The third number is found by dividing the sum of the two others by 2; the unregistered cases being, as before stated, one-third of the whole.