It will, I hope, be needless to tell the reader, that I have disclosed the whole of what I know with certainty relative to this process, as the regimen, medicines, different types of the disease, the rules of prognostic, and various events, &c. are fully and faithfully related, according to the best of my judgment and experience. And I believe, if the method now recommended is carefully pursued, it will be found to answer with a success at least equal to any yet discovered. Nevertheless it is reasonable to suppose, that further experience may produce some improvements: yet when it is considered, how short a time is required for preparation; how few medicines are to be taken; that those medicines are neither nauseous in themselves, nor violent in their operation, and of a kind likely to be beneficial to most constitutions, and hurtful to none, unless injudiciously administered; that the disease is usually so mild, as to require little or no confinement (the complaints of far the greater number being that they have too little of the distemper); and that the disagreeable consequences which sometimes happened after the former method of inoculation are likewise by this most commonly obviated; I do not see that much alteration can be even wished for. That which appears most likely to be made, is in shortening the time of preparation; for as I have often been obliged to inoculate without any, and have always had the same success, it has inclined me to think, that much, if not the whole, of this process, may be dispensed with, except in very full habits, or where other particular circumstances may require it. But in all these cases, from the insertion of the matter to the time of the eruptive complaints, the patients have been kept to a close observance of diet, and the use of the preparatory medicines, proportioned as well as I could to their condition: for I durst not, by way of experiment, dispense with the use of measures that had been hitherto so successful. Should it be asked then, To what particular circumstance the success is owing? I can only answer, that although the whole process may have some share in it, in my opinion it consists chiefly in the method of inoculating with recent fluid matter, and in the management of the patients at the time of eruption. If these conjectures should be true, perhaps we should be found to have improved but little upon the judicious Sydenham’s cool method of treating the disease, and the old Greek woman’s method of inoculating with fluid matter carried warm in her servant’s bosom. CASES. CASE I. Nov. 23d. A very strong, fat, middle-aged man was inoculated with fluid matter, from a person pretty full of the natural small-pox, and near the crisis. 26th. He came to me, that I might inspect the arm, which then appeared to be certainly infected, and very forward.