In an appendix to his seventh article, he discusses the writings of certain Italian, French and German scientists, giving his reasons for differing with them on certain philosophical questions. His discussion is devoted largely to a consideration of certain laws of hydrostatics. His "Observations on the eclipse of the sun, June 16, 1806" made in his private observatory on Union Hill, constitutes his tenth contribution to the publication mentioned above. This article gives a vivid account of the excited state of mind with which an astronomer awaits the time when nature affords favorable opportunities for investigating her mysteries. It also shows that this frontier scientist of Mississippi enjoyed in thought, as he could not by personal association, the companionship of the great thinkers of the world. These are his words: "The moment of the expected impression approached and reflecting that this eclipse was to be seen all over Europe and North America which renders it a very important phenomenon for settling comparative longitudes, I conceived that all the zealous astronomers of both worlds were then looking with me at the great luminary and centre of our system. I kept my eye riveted upon that point of the disk where the eclipse was to commence, with an anxiety known only to astronomers; with the chronometer watch at my ear, I attended to the most doubtful appearances which my perturbation perhaps presented to the eye, and upon every alarm, began to count the beats of the watch (five in two seconds) in order that I might not lose the very first instant of the impression, and I am confident that not one quarter of a second was lost." The last letter that has been preserved from the interesting correspondence between Dunbar and Jefferson, bears the date of Dec. 17, 1805. With it was enclosed Dunbar's "Method of finding the Longitude by a single observer without any knowledge of the precise time," a problem that had been solved by him at Jefferson's request. This formed an eleventh contribution to the publication referred to above. There is no reason for doubting that this correspondence was continued throughout the remaining four years of Dunbar's life, though the letters have not been found by the writer. Dunbar's last contribution to the Transactions was entitled: "Observations on the Comet of 1807-'8." It was read before the Society Nov. 18, 1808. In this article appears at least one entry which indicated that the scientific services of its author were drawing to a close. "Indisposition," says he at one point in the narrative, "prevented observation for some time past." A few months from this date the scientific investigation of this remarkable man were brought to a close.