I shall not weaken the force of this evidence by entering into any minor question connected with this great subject—such as the probability of many of those, in whom Small Pox has succeeded to Vaccination, having passed through the latter process imperfectly, either in consequence of the matter employed not having been genuine; of the constitution not having shown adequate signs of being properly influenced by the process; or of the latter having been interfered with in its progress, by the accidental injury of the pustules, &c. No doubt all these causes may have had some effect, in consequence of the carelessness of parents, or of the practice of non-professional inoculators: in a matter of so much importance then, it behoves parents to guard against these causes of failure, which it is now certainly within the power of the poorest to do. Nor shall I detail the arguments by which Professor Thomson has rendered it probable that the pustular eruption, which has been so long known in this country under the name of Chicken Pox, is very nearly related to Small Pox itself, and is in reality the effect of the same infectious virus modified by various incidental circumstances; such as season of the year, the previous existence of Small Pox or of Cow Pox in those affected by it, or some peculiarity in their constitution not sufficiently obvious to be recognised by our senses. When I rest my proof of the power of Vaccination over the destructive consequences of Small Pox on the results which have been detailed, I am satisfied that it is fixed upon a basis too firm to be shaken by argument, and which will long outlive the feeble attacks of ignorance or prejudice. ------------------------------------------------------------------------ CONCLUSION. The following are the important conclusions which may obviously be deduced from the satisfactory evidence which has been detailed. 1. That Vaccination has, within the space of twenty-five years, been the direct means of preserving, within the London[8] Bills of Mortality alone, a number of lives amounting to 21,127; and that if we extend the ratio of calculation to the whole of Great Britain and Ireland, it will appear that not fewer than 393,356 lives have been saved by this most valuable discovery, while an equal number have been preserved from “blindness, deformity, scrofula, or broken constitutions.” ----- Footnote 8: