The scientific world are indebted to this excellent practical astronomer for the publication of the Nautical Almanack; and, in a great measure, for the perfection of the lunar method of ascertaining the longitude at sea. “His unwearied exertions in this great cause of humanity and science,” as the compilers of the New Edinburgh Encyclopedia (in the article Astronomy) observe, “entitle him to the gratitude of the remotest posterity.”
[128]. It appears that the difference of the meridians of the Greenwich and Paris Observatories, is 9′ 20″ as assumed by Lalande. This was ascertained by the result of the measurement of the distance between those Observatories, made sometime about the year 1786 or 1787, under the sanction of the British and French governments, respectively; and this difference of meridians corresponds with what Dr. Maskelyne had before stated it to be. The last mentioned astronomer shewed, in 1787, that the latitude of Greenwich is 51° 28′ 40″.
[129]. In relation to Paris, Mr. Lalande calculates the longitude of Philadelphia at 5h 9′ 56″, according to Mr. Rittenhouse; and its latitude, as being 39° 5′7 10.
[130]. In Mr. Rittenhouse’s “Delineation of the Transit,” &c. published in the first volume of the Philosophical Society’s Transactions, it appears that he assumed the latitude of the Norriton Observatory to be 40° 9′ 56″.
[131]. See Martin’s Philosophia Britannica, lect. xi. note 141. Though “Orrery” be a modern name, the invention of such machines as it is now applied to, is of a very early date. The first planetarium or orrery, of which we have any account, was the famous machine of Archimedes. This consisted, as Cicero (in his Tusculan Questions) asserts, of a sphere, of an hollow globular surface, of glass, within which was some ingenious mechanism, to exhibit the motions of the moon, the sun, and all the planets then known. Very imperfect as it must necessarily have been in other respects, it was radically erroneous, in being adapted to the Ptolomaic system. This is described in Latin verse, by the poet Claudius Claudianus, of Alexandria, who flourished about four centuries after the Christian era, and more than six centuries after the Syracusean philosopher.
Cicero, in his book De Naturâ Deorum, mentions one invented by Posidonius the Stoic, in his time, and about eighty years before the birth of Christ. He describes it as a “sphere,”—“in every revolution of which, the motions of the sun, moon, and five planets were the same as in the heavens, each day and night.”
Nothing further is heard of orreries or spheres, until about five hundred and ten years after Christ, when Anicius Manlius Torquatus Severinus Bœthius, the Roman Consul, (who was also a Christian, and a Peripatetic Philosopher,) is said to have contrived one. Theodoric, king of the Goths, calls it “Machinam Mundo gravidam, Cœlum gestabile, Rerum Compendium”: But Bœthius was, nevertheless, put to death by this Gothic king, A. D. 524. A long and dismal reign of barbarism and ignorance having succeeded this period, no further mention is made of any thing in the nature of a planetarium, for about one thousand years. See Note [95].
[132]. In the work, entitled, “A new and general Biographical Dictionary,” &c. published in 1761, the Invention of Graham’s Planetarium is attributed to the celebrated Charles Boyle, Earl of Orrery; and the compilers of that work cite this supposed Invention of Lord Orrery, “as an indubitable proof of his mechanical genius.” On this authority, the compilers of the British Encyclopædia (reprinted in Philadelphia by Mr. Dobson,) in the very words of the Biographical Dictionary, make the nobleman from whom the first English Orrery derives its name, the Inventor. But it seems to be now pretty generally admitted, that his lordship was only the Patron of the machine, made for George I. by Mr. Rowley.
[133]. This accomplished nobleman, who was also the fourth Earl of Cork, in Ireland, and the third Earl of Burlington, in England, was born in the year 1695, and died in 1753. He was a great encourager of the liberal arts, possessed an extraordinary taste and skill in architecture, and was animated by a most exalted public spirit.
[134]. Mr. Martin (in his Philosophia Britannica) says: “The Orrery, though a modern name, has somewhat of obscurity in respect to its origin; some persons deriving it from a Greek word, which imports to see or view:” “But others say, that Sir Richard Steele first gave this name to an instrument of this sort, which was made by Mr. Rowley for the late Earl of Orrery, and shewed only the movement of one or two of the heavenly bodies. From hence many people have imagined, that this machine owed its invention to that noble lord.” This Orrery was a large one; and, although it is represented by Mr. Martin as a very defective machine, it was purchased by King George I. at the price of one thousand guineas.