Daring the occupancy of Philadelphia by the British forces under Sir William Howe, the commander in chief, from the 26th of September, 1777, until the evacuation of that city on the 18th of June, in the following year, Mr. Rittenhouse resided at Lancaster;[188] where he was busily employed in the duties of his office of treasurer of the state.[189] Before his removal from Philadelphia, he had placed his family at or in the vicinity of his farm in Norriton, distant about twenty miles in a north-westwardly direction from the capital; then conceiving that situation to be a place of safety from any hostile excursions. While he himself continued in the borough of Lancaster, he made his home at the house of the late William Henry, Esq. at that time treasurer of the rich and populous county of the same name; a situation which was very commodious for the business of his office, from its connexion with that of the county-treasurer, and one which was also rendered the more agreeable, by reason of Mr. Henry being a person of very considerable mechanical ingenuity. ----- Footnote 188: This large and thriving borough, said to be the greatest inland town in the United States, was, for a short time, (though very short, indeed,) the seat, or rather place of refuge, of the American congress; the members of which, having separated on the near approach of the British army, eight days before their occupation of the capital, re-assembled at Lancaster the 27th day of the same month. Lancaster, which is situated at the distance of sixty-four miles from Philadelphia, in a direction nearly west, was at first conceived to be a place of safety: but, for their more perfect security, congress convened, three days afterwards, at York in Pennsylvania, a considerable county-town about twenty-two miles westward from Lancaster, and from each of which places, the intervening great river Susquehanna is about equidistant. Footnote 189: His active mind derived much of its happiness from its continual employment. It appears, that, while engaged in the duties of his office, at Lancaster, in the latter part of the year 1777, he made the calculations for an Ephemeris, called “Father Abraham’s Pocket-Almanack, for the year M.DCC LXXVIII;” the late Mr. John Dunlap, the publisher, (who was, during many years, an eminent printer in Philadelphia,) having, in his advertisement of it, announced to the public, that “The Astronomical Calculations of this Almanack were composed by David Rittenhouse, A. M.” Mr. A. Ellicott made calculations for Pennsylvania and Maryland Almanacks, several years after Mr. Rittenhouse declined to continue them.