It is foreign to my purpose to deliver to you the history of this art, and to mark the various steps that have attended its progress to its present state of improvement. We have yet to lament the want of uniformity and of equal success in the practice of it among physicians. A great number of pamphlets have been written upon the subject without exhausting it. There is still ample room left for the man of genius to exercise his talents for observation and reasoning upon it. The facts I mean to lay before you are so inconsiderable, compared with what still remain to be known upon this subject, that I have to request, when your knowledge in it is completed, that you would bury my name in silence, and forget that ever I ventured to lay a single stone in this part of the fabric of science. In treating upon this subject, I shall I. Consider the proper subjects, and seasons for inoculation. II. I shall describe the method of communicating the disease. III. I shall consider the method of preparing the body for the small-pox. IV. I shall mention the treatment proper during the eruptive fever. And, V. Point out a few cautions that are necessary after the disease is over. I. Formerly there were great difficulties in the choice of subjects for inoculation. But experience teaches us, that it may be practised in every stage of life, and in almost every condition of the human body. In infancy, the periods before and after dentition are to be preferred. But we seldom see any great inconveniences from submitting to the general necessity of inoculating children between the ages of three months, and two years. Indeed we often see children cut three or four teeth during the preparation and eruptive fever, without the least addition being made to any of the troublesome symptoms which accompany the small-pox. There is one inconvenience attending the choice of the first months of infancy for inoculating, and that is, the matter often fails of producing the disease in such young subjects. I have frequently failed in two or three attempts to communicate it to children under four months old, with the same matter that has succeeded in a dozen other patients, inoculated at the same time. When the inoculation succeeds in such tender subjects, they generally have less fever, and fewer pustules, than are common in any future period of life.