Mr. Cross relates that _two_ deaths only took place after Vaccination, and justly observes, that “these can have no weight against the practice of Vaccination compared with 10,000 vaccinated individuals, living in the midst of a contaminated atmosphere; with 530 deaths among little more than 3000 who had neglected to be vaccinated; and with the occasional occurrence of regular Small Pox in those who formerly had the disease.” Of the 10,000 persons thus protected by Vaccination, the Reviewer of Mr. Cross’s History, &c. observes (Edin. Med. and Sur. Journal, Vol. xvii. p. 127), “Had these persons been protected by variolous (Small Pox) inoculation, conducted in the best manner, and in the most favourable circumstances, at least 33 of them (1 in 300) would have died of the process intended to protect them; so that in comparing the advantages of the two methods of protection, we have to weigh 33 deaths _certain_, against _two contingent on the invasion of an epidemic Small Pox_, and then we have to consider, whether there might not be nearly as great a chance of _two persons_ out of 10,000 inoculated for Small Pox, taking a fatal Small Pox on exposure, at a subsequent period of life, to a virulent contagion.” I shall conclude the evidence I think it necessary to bring forward on this part of my subject with the following extract from the Report of the National Vaccine Establishment for 1820. In reference to the occasional cases wherein the protection from Vaccination is not quite complete, the Board observes,—“Yet the value of this important resource is not disparaged in our judgment; for after all, these cases bear a very small proportion to the number of those who are effectually protected by it. The reports of the Vaccinators at the several stations in the metropolis, give only _eight_ cases of Small Pox out of nearly 67,000 vaccinated by them, since the first establishment of this board; and as the Small Pox has prevailed extensively in London, these persons so vaccinated, must have been frequently exposed to contagion, and consequently the protecting effect of Vaccination must have been submitted to as severe a test as can well be imagined. Moreover, we have the most undoubted proofs from experience, that where Vaccination has been performed perfectly, Small Pox, occurring after it, is almost universally a _safe_ disease; and though ushered in by severe symptoms, has hardly ever failed to be cut short before it had reached that period at which it becomes dangerous to life.”