In 1677 the town of Boston was besieged by one of the worst smallpox epidemics in its history. At that time Castle Island was the site where incoming vessels stopped to declare their customs duties and let the Captain of the Island, at that Edward Rawson, about any infection on board ship. Two remarkable letters have recently been discovered that discuss the quarantine of infected vessels that arrived during the summer of 1677. One was commanded by Captain Legg and the other by Captain Semmor - possibly a deviant spelling of Seymour. Captain Legg was ordered to quarantine on Deer Island as the following transcript of Rawson's order reveals. Special dispensation was allowed for pregnant woman who was near her time of delivery. An image of that letter is also shown below in the handwriting of Edward Rawson (his initials are evident at the bottom of the order). "Ordered that for prevention of infection by any of the passengers in Mr. Legg’s Ship that has by the hand of God bee