Hunter was for many years in the habit of mentioning it in his public lectures coupled with Jenner’s name: but the proposed substitution was so distasteful, or appeared of such questionable propriety, that it obtained no favourable notice till it was forced by the inventor on the public attention, thirty years after it had first attracted his own. It would be interesting to enter into a detail of the progress of Jenner’s discovery and of its introduction into general use, as well as to show its inestimable value to society by a reference to statistical facts. This, however, can only be done here in a very cursory manner. The way in which the idea was first suggested to him has been already mentioned. After his return to Berkeley from London, he pursued the subject with great patience and sagacity for many years. In the course of these preliminary inquiries he found reason to believe that of several kinds of vesicular disease in the cow, but one had the property of securing from the small-pox, and that one exclusively, or at least with the greatest certainty, in its first stage. He also ascertained that the horse is subject to an eruption of similar vesicles, apparently arising without infection, and popularly known by the name of the _grease_. The matter issuing from these is sometimes conveyed to the cow by milkers engaged in farriery; and Jenner conceived it to be the original and only source of cow-pox among the herds. The opinion is not generally held at present to its full extent; but experiments by himself and others since the publication of his Inquiry have proved a fact much disputed at the time, that he was right in believing the diseases to be identical, whatever may be their origin. It may be mentioned as a curious circumstance, that the first lymph transmitted in an active state to British India in 1802 by Dr. De Carro of Vienna, long the only source of vaccination in that country, had been furnished to him by Dr. Sacco of Milan, from genuine vesicles produced by direct inoculation from the horse, without passing through the cow; an intervention which, till about that period, Jenner had continued to think essential to the production of the true disease in man. In addition to these and other curious results, laboriously collected during a period of twenty-six years, Dr. Jenner at length arrived at a rational conviction of the safety of the experiment he meditated, from observing the invariable harmlessness of the disease when casually taken: he determined therefore to put his long-cherished idea to the trial on the first opportunity. This offered on the 14th of May, 1796, the anniversary of which is still kept as a festival at Berlin. On that day he inoculated a boy of the name of Phipps in the arm, from a pustule on the hand of a young woman who was infected by her master’s cows. The boy went favourably through the disease. On the 1st of July he was inoculated for the small-pox, and, as Jenner had predicted, without effect.