Although a physician would prefer a patient in good health to any other as a subject for inoculation, yet cases often occur in which it is necessary to communicate the small-pox while the body is affected with some other disease. I can with pleasure inform you, that the small-pox is rendered so perfectly safe by inoculation, that there are few chronic diseases which should be considered as obstacles in the way of it. I have inoculated patients labouring under a tertian fever, obstructed viscera, the hooping cough, the hypochondriasis, the asthma, the itch, and other cutaneous diseases, and even pregnant women, with the same, and, in some instances, with greater success, than persons in perfect health. Doctor Cullen informs us, that he has seen inoculation succeed in scrophulous patients. A physician in Jamaica informed me, that he had inoculated negroes with success in the worst stage of the yaws. To these facts I must add one more extraordinary than any that has been yet mentioned: Doctor Brown, my late colleague in the care of the military hospitals, informed me, that he had seen inoculation succeed in patients who were seized, after the infection was communicated, with the hospital fever. The preparation of the body should be accommodated to the disease which affects it. Some physicians have thought the small-pox, received in this way, was a remedy for other diseases; but my experience has not confirmed this opinion: on the contrary, I am inclined to think that no other change is produced by inoculation, than by the regimen and medicines that are used to prepare the body for the small-pox. Nor does the small-pox, during its continuance, afford any security against the attacks of other diseases. I have seen the most alarming complication of the small-pox and measles taken in _succession_ to each other, in the same person. The seasons commonly preferred for inoculation, in this country, are the spring and fall. It may be practised with equal safety in the winter, a due regard being had to the temperature of the air in the preparation of the body. The principal objection to inoculating in the summer months in this climate, arises from the frequency of bilious diseases at that season, to which the preparation necessary for the small-pox probably disposes the body. This caution applies more directly to children, who, at a certain age, are more subject than grown people to a disease in their bowels in warm weather. II. The methods of communicating the small-pox by inoculation, have been different in different countries, and in the different æras of its progress towards its present stage of improvement. The scab, dossel of lint, and the thread impregnated with variolous matter, and bound up in a gash in the arm, have been laid aside.