^* The significance of the Transit of Venus was first pointed out by Dr. Halley, in a paper read before the Royal Society in the year 1691, On the Visible Conjunctions of the Inferior Planets with the Sun.—Philos. Trans. (abridged edition), vol. iii, p. 448. He demonstrated that by the observation of this phenomenon alone, the distance of the sun from the earth might be determined with the greatest certainty. He returned to the subject in 1716, in another paper, On a New Method of Determining the Parallax of the Sun or his Distance from the Earth.—Philosophical Transactions (abridged edition), vol. vi, p. 243. The observations of the first Transit of Venus, which occurred after the publication of Halley's “new method,” were not very successful. Some of the calculations were erroneous; and, as one of the consequences, the most favourable localities were not used as observing-stations. When the time approached for the second Transit—viz., that of 23rd May, 1769—the Royal Society determined to make amends. The matter was successfully represented to the Government of the day—that of the Earl of Chatham. The Endeavour was placed at the disposal of the Royal Society. Cook, then a master, was raised to the rank of lieutenant, placed in command by the Admiralty, and selected by the Royal Society to observe the Transit in conjunction with Mr. Green. The island of Otaheite, then newly discovered by Wallis, was selected as the observing-station. The history of the expedition will be found at length in Hawkesworth's Voyages, vols. ii and iii.