Note 111 — MEMOIRS OF THE LIFE OF DAVID RITTENHOUSE; ANTERIOR TO HIS SETTLEMENT IN PHILADELPHIA.

It was not until the year 1786, that Mr. Rittenhouse built the house at the north-west corner of Arch and (Delaware) Seventh streets, in Philadelphia, where he resided during the remainder of his life: but probably it was some few years earlier that he erected his Observatory, a small but pretty convenient octagonal building, of brick, in the garden adjacent to his dwelling-house. Its situation was not an ineligible one, when the building was first put up: but its commodiousness and utility were probably much diminished, by the erection, not long afterwards, of some large houses near it; and it is presumable, that its usefulness in any degree, for the purposes of an Observatory, could have continued but a little while beyond the duration of its late proprietor’s life, by reason of the rapid increase of the number of lofty houses in the vicinity. Indeed it lately became extremely probable, on considering the great enlargement of Philadelphia within the last twenty-five years, that the future augmentation of the population and extension of improvements in this beautiful and hitherto flourishing city, would, in a very few years, render the late Observatory of Mr. Rittenhouse wholly useless for astronomical purposes; and, in the event of the surrounding ground and adjacent buildings being alienated from his family, improper for any other.

This was the Observatory noticed by Mr. Lalande, when (in his Astronomie, published in 1792,) he made this remark, treating of the numerous Observatories in different parts of the world—“In America, I know of no Observatory but that of Mr. Rittenhouse at Philadelphia.”

The Observatory at Norriton, mentioned in the text, was a temporary erection; and was disused on his removal to Philadelphia, soon after. The one put up in the State-House Gardens in that city on the same occasion, was likewise a temporary edifice, constructed of wood.