Fleets' pocket almanack for the year of our Lord 1791 [electronic resource] : Being the third after leap year, and fifteenth of American independence. Calculated chiefly for the use of the Commonwealth of Massachusetts, Boston, the metropolis, being in latitude 42 deg. 25 min. north. Longitude 71 deg. 4 min. west from the Royal Observatory at Greenwich. : To which is annexed, the Massachusetts register. &c