My surprise at this sudden transition from extreme sickness to health in great measure ceased when I observed that the inoculated pustule had occasioned, in this case, the common efflorescent appearance around it, and that as it approached the centre it was nearly in an erysipelatous state.  But the most remarkable part of this history is that, on the fourth day afterwards, so soon as the efflorescence began to die away upon the arm and the pustule to dry up, the scarlatina again appeared, her throat became sore, the rash spread all over her.  She went fairly through the disease with its common symptoms.

That these were actually cases of scarlatina was rendered certain by two servants in the family falling ill at the same time with the distemper, who had been exposed to the infection with the young ladies.

Some there are who suppose the security from the smallpox obtained through the cow-pox will be of a temporary nature only.  This supposition is refuted not only by analogy with respect to the habits of diseases of a similar nature, but by incontrovertible facts, which appear in great numbers against it.  To those already adduced in the former part of my first treatise [Footnote:  See pages 217, 218, 219, 221, 223, etc.] many more might be adduced were it deemed necessary; but among the cases I refer to, one will be found of a person who had the cow-pox fifty-three years before the effect of the smallpox was tried upon him.  As he completely resisted it, the intervening period I conceive must necessarily satisfy any reasonable mind.  Should further evidence be thought necessary, I shall observe that, among the cases presented to me by Mr. Fry, Mr. Darke, Mr. Tierny, Mr. H. Jenner, and others, there were many whom they inoculated ineffectually with variolous matter, who had gone through the cow-pox many years before this trial was made.

It has been imagined that the cow-pox is capable of being communicated from one person to another by effluvia without the intervention of inoculation.  My experiments, made with the design of ascertaining this important point, all tend to establish my original position, that it is not infectious except by contact, I have never hesitated to suffer those on whose arms there were pustules exhaling the effluvia from associating or even sleeping with others who never had experienced either the cow-pox or the smallpox.  And, further, I have repeatedly, among children, caused the uninfected to breathe over the inoculated vaccine ’pustules during their whole progress, yet these experiments were tried without the least effect.  However, to submit a matter so important to a still further scrutiny, I desired Mr. H. Jenner to make any further experiments which might strike him as most likely to establish or refute what had been advanced on this subject.  He has since informed me “that he inoculated children at the breast, whose mothers had not gone through either the smallpox or the cow-pox;