“There is perhaps no individual of the present age,” (says the writer of the article “Astronomy,” in the New Edinburgh Encyclopædia, now publishing under the direction of Dr. Brewster,) “to whom practical astronomy owes deeper and more lasting obligations, than to Mr. Edward Troughton. The great improvements which he has made upon astronomical instruments, and the extreme accuracy with which he divides them, have rendered his name celebrated in every part of Europe, and have inspired the practical astronomer with a confidence in his observations, which he had hitherto been unaccustomed to feel. There is scarcely an observatory of any consequence, either in this country” (Great-Britain,) “or the continent, that does not contain some of Mr. Troughton’s instruments; and there are few series of observations, in which they have not been used. The admirable observations of Mr. Pond, on the declinations of the principal stars, were made with an azimuth circle of Mr. Troughton’s construction. The mural circle, which Mr. Groombridge of Blackheath uses, in his numerous and accurate observations, was made by the same artist. The splendid mural circle, of 6 feet 2 inches radius, which Mr. Troughton is at present preparing for the Royal Observatory at Greenwich, will cost 700_l._” (equivalent, in money of the United States, to $311111/100,) “and will be one of the most magnificent and accurate instruments that has ever been erected.” ----- From the time our astronomer became established in Philadelphia, until the year 1787, he resided in a house belonging to the late Mr. Thomas Clifford, at the south-east corner of Arch and (Delaware) Seventh streets: But the mansion which Mr. Rittenhouse had erected for himself, the preceding year, on his Observatory-lot at the diagonal corner of those streets, being then compleated, he removed thither; and there continued his residence, during the residue of his life. It was about this time, perhaps towards the close of the year 1786, that he was compelled by the duties of his office, as sole trustee of the loan-office, to put in suit the bonds which accompanied the mortgages of sundry delinquent loanees. The bonds were placed in the hands of the Writer of these Memoirs, for that purpose; with instructions to treat the delinquents with every reasonable degree of forbearance. This lenity was observed, agreeably to Mr. Rittenhouse’s desire; few suits were instituted, and payment of the monies due, or the greater part of them, was not long after obtained. Early in the year 1787, the expected appearance of a new comet in that year, engaged Mr. Rittenhouse’s attention: and on that occasion he addressed the following letter to Mr. Ellicott. “_Philadelphia, Feb. 12, 1787._ “Dear Sir,