Note 231 — MEMOIR OF THE LIFE OF DAVID RITTENHOUSE; CONTINUED, FROM THE TIME OF HIS SETTLEMENT IN PHILADELPHIA.

“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 700l.” (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.”