<Tr> <Td> "</Td> <Td>... scarred the wrists, legs, and forehead of the patient, placed a fresh and kindly pock in each incision and bound it there for eight or ten days, after this time the patient was credibly informed . The patient would then develop a mild case (of smallpox), recover, and thereafter be immune . </Td> <Td>" </Td> </Tr> <Tr> <Td_colspan="3">--Dr. Peter Kennedy </Td> </Tr> <P> Stimulated by a severe epidemic, variolation was first employed in North America in 1721 . The practice had been known in Boston since 1706, when Cotton Mather (of Salem witch trial fame) discovered his slave, Onesimus had been inoculated while still in Africa, and many slaves imported to Boston had also received inoculations . The practice was, at first, widely criticized . However, a limited trial showed six deaths occurred out of 244 who were variolated (2.5%), while 844 out of 5980 died of natural disease (14%), and the process was widely adopted throughout the colonies . </P> <P> The inoculation technique was documented as having a mortality rate of only one in a thousand . Two years after Kennedy's description appeared, March 1718, Dr. Charles Maitland successfully inoculated the five - year - old son of the British ambassador to the Turkish court under orders from the ambassador's wife Lady Mary Wortley Montagu, who four years later introduced the practice to England . </P>

When did scientists discover the cause of smallpox