In respect to constitution, greater liberties may be taken than have heretofore been judged admissible: persons afflicted with various chronic complaints, of scrophulous, scorbutic, and arthritic habits; persons of unwieldy corpulency, and of intemperate and irregular lives, have all passed through this disease, with as much ease and safety as the most temperate, healthy, and regular. But those who labour under any acute or critical diseases, or their effects, are obviously unfit and improper subjects. So likewise are those where there are evident marks of corrosive acrimonious humours, or where there is a manifest debility of the whole frame, from inanition, or any other cause: all these should be treated in a proper manner previous to the introduction of this disease. Constitutions disposed to frequent returns of intermittents, seem likewise justly exceptionable; especially as the preparatory regimen may in some habits increase this tendency. I have known, however, instances of severe ague fits attacking persons between the insertion of the matter and the eruption of the pock, and even during maturation; when the Peruvian bark has been given liberally and with success; the principal business, in the mean time, suffering no injury or interruption. Among the circumstances generally considered as more or less propitious to inoculation, the season of the year has hitherto been deemed a matter of some importance. Spring and autumn, for the most part, have been recommended, as being the most temperate seasons; the cold of winter, and the summer heats, having been judged unfavourable for this process. But experience does not justify these opinions; for according to the best observation I have been able to make, inoculated persons have generally had more pustules in spring than at any other time of the year; and epidemic diseases being commonly most frequent in autumn, especially fluxes, intermittents, and ulcerated sore throats (all which are liable to mix more or less with the small-pox) the autumn, upon this account, does not seem to be the most favourable season in general. My opinion is, that considering the surprizing and indisputable benefits arising at all times to patients in the small-pox, from the free admission of fresh cool air and evacuations (which will appear from some cases hereafter subjoined) we may safely inoculate in all seasons, provided care be taken to screen the patients as much as possible from heat in summer, and to prevent them from keeping themselves too warm, and too much shut up, as they are naturally disposed to do, from the weather in winter. And it is well known, that many have been inoculated in the depth of winter, and some during the greatest heat in summer, without suffering any injury or inconvenience from either.