In regard to age; where it is left to my choice, I decline inoculating children under two years old. I know the common practice is against me in this particular; but my reasons for rejecting such are founded on observation and experience. I have, indeed, lately inoculated many under this age, at the pressing entreaties of their parents, and they have all done well. But it must be considered, that young children are exposed to all the hazards of dentition, fevers, fluxes, convulsions, and other accidents, sufficiently difficult in themselves to manage in such tender subjects; insomuch that scarce two in three of all that are born, live to be two years old, as is demonstrable from the Bills of Mortality. Besides, convulsive paroxysms often accompany the variolous eruptive fever in children; and though generally looked upon in no unfavourable light, as often preceding a distinct kind of small-pox, yet they are at all times attended with some degree of danger; nay, some, it is well known, have expired under them; while others, who have struggled through with great difficulty, have been so debilitated, and their faculties so impaired, that the effects have been perceptible during the remaining part of their lives. And even admitting the eruption to be favourable, and not attended with any such alarm, yet should a larger number of pustules than usual appear, or any untoward symptom happen, and require medical help, the unhappy sufferer is much too young to be prevailed on to take unpalatable medicines, or submit to other necessary measures, by persuasions, menaces, or bribes. I have often been present at afflicting scenes of this nature; and have reason to think that many children have died of the small-pox in the natural way, merely from the impossibility of prevailing upon them to comply with what was proper, in cases where little or no danger was discoverable, either from the number or species of the pustules, the degree of fever, or any other apparent cause. It must likewise be taken into consideration, that young children have usually a larger share of pustules from inoculation, than those who are advanced a little farther in life; and that under this circumstance many have died; and the proportion of these, so far as I can learn, is too great to encourage a continuance in the inoculation of young children: so that it seems most prudent to wait till this dangerous period be over, especially as its duration is so short, that the danger of their receiving the small-pox therein in the natural way is very little; and it is at this time much more easy to preserve them from it, than when they are left more to themselves, and may be more in the way of infection. But children above this period may be inoculated more freely; nor does there appear any reason to exclude healthy adults of any age; persons of seventy having passed through this process with the utmost ease, and without occasioning the least painful apprehension for the event.