In addition to his duties as the Sally's captain, Esek Hopkins served as the ship's "supercargo," the officer in charge of the cargo. During the long voyage, he kept a detailed account book, recording every trade and transaction. The book included a page for each crewmember, showing advances on wages, purchases of clothing and rum from the ship's stores, and so forth. Transactions on the African coast, where the Sally arrived in early November, 1764, begin on page 17 and continue for the next seventy pages. The accounts specify the date on which each enslaved African was acquired and what was traded for him or her. Most of the transactions were recorded in "barrs," a unit frequently used in the slave trade. A "barr" was literally an iron bar, but it was also a monetary equivalent - thus a yard of cloth was accounted at once bar, a barrel of rum at ten bars, and so forth.Throughout the long voyage, Hopkins kept a running tally of the total number of Africans he had purchased. By the time the Sally left Africa in August, 1765, he had acquired 196 Africans, at least twenty one of whom he sold to other traders before leaving the coast. Another nineteen had died, and a twentieth was left for dead on the day the ship sailed. Dozens more would die on the transatlantic passage or in the days after the Sally's arrival at the West Indian island of Antigua. In all, the account book records the loss of 109 enslaved Africans, as well as three of the Sally's crew.