Like the mill, the original house on the hilltop was built of rough-hewn native stone, which is brown or red and very hard. It consists of two stories, with central hall, and a curiously divided attic with dormer windows, which Audubon is said to have converted into a museum. A marble slab in the south gable bears the date of 1762; an addition of the same rough stone was built on the north side, but at a considerably lower level, in 1763, and the commemorative tablet in this instance bears the initials "J. M.," proving that the construction of the buildings of "Mill Grove" was due to the old miller, James Morgan. The interior, with its odd chimney-corner, low ceilings, bold fireplace and hand-wrought iron-work, bears witness to a time when honest, substantial construction and pride in workmanship received the first consideration. The present owner of "Mill Grove" has added attractive porches at the front and back. Ampelopsis climbs over the walls, which are shaded by handsome trees; one of these, a fine black walnut at the easterly porch, which in August bore its great green balls in full clusters, must have been vigorous in Audubon's day, and possibly suggested the introduction of sprays of this full-fruited tree into some of his plates. While on a visit from Santo Domingo in 1789, concerned with his business interests, Captain Audubon spent some time in Philadelphia. On March 28, 1789, he purchased the "Mill Grove" property, at that time consisting of 284½ acres of land, mansion house, mill, barns, furniture, tools and live stock, from Henry Augustin Prevost[86] and his wife, for the sum of 2,300 English pounds, in gold and silver. He never lived there, and that he never intended to make it his immediate residence is shown by the fact that in less than a fortnight he leased the farm in its entirety, as already noticed, to its former owner, and gave him a mortgage which stood for seventeen years.[87] Young Audubon lived at "Mill Grove" from the winter of 1804 to the spring of 1805, and again for a few months in the summer of 1806, the year of its final sale by the Audubons and Roziers (see p. 148). In his journal of 1820 the naturalist wrote that his father had once the honor of being presented to General Washington, and also to Major Crogan, of Kentucky, "who was particularly well acquainted with him." Jean Audubon left at "Mill Grove" oil portraits of himself and of Washington, both by an inferior American artist named Polk,[88] and it is probable that the one of himself was painted while he was at Philadelphia in the spring of 1789; the drawing is hard and flat, but the appearance of the face clearly indicates a man past middle life, and Captain Audubon had then reached his forty-fifth year.