Although such was the keen sensibility of this amiable man, on so distressing an occasion, his numerous avocations of business and studies, aided by the correctness of his own reflections, gradually dispelled these over-shadowings of his dejected mind; and ere long, he very naturally regained his usual serenity and cheerfulness of temper. A new phænomenon in the heavens soon after engaged his attention: this was the Comet which appeared in June and July, 1770. His Observations on this Comet, with the elements of its Motion and the Trajectory of its Path, were communicated to the American Philosophical Society, through his friend Dr. Smith, on the 3d of August, soon after the Comet’s disappearance, and were dated at Norriton the 24th of the preceding month. The letter to Dr. Smith, that covered this communication, and in which he says, “Herewith I send you the fruit of three or four days labour, during which I have covered many sheets, and literally drained my ink-stand several times”—will demonstrate how completely his mind was occupied in those researches. About the close of the following autumn, some accounts of Observations of this Comet in England and France, respectively, reached this country, when a further correspondence on the subject took place between Dr. Smith and Mr. Rittenhouse. These communications are published, entire, in the first volume of the Philosophical Society’s Transactions; and, with those already noticed, complete the list of our Astronomer’s papers in that volume. It is here worthy of remark, that a comparison of Mr. Rittenhouse’s Observations of this Comet with those of M. Messier in France and Mr. Six in England, confirmed the theory of the American Observer. Before this subject is dismissed, however, it may not be deemed uninteresting to subjoin an extract of a letter which Mr. Rittenhouse addressed to the Rev. Mr. Barton (from Norriton,) on the 30th of July, respecting the same Comet: it will, at least, serve to shew the zeal of our Astronomer, on the occasion.