Part 32

Footnote 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″.

Footnote 129:

In relation to Paris, Mr. Lalande calculates the longitude of Philadelphia at 5^h 9′ 56″, according to Mr. Rittenhouse; and its latitude, as being 39° 5′7 10.

Footnote 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″.

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The same Volume of the American Philosophical Transactions that comprehends the communications of these Proceedings—as well as various Observations, made at different places, on the then recent Transit of Venus—contains also a Memoir, by Dr. Smith, deducing the Sun’s Parallax from a comparison of the Norriton and some other American Observations of the Transit of Venus, in 1769, with the Greenwich and some other European Observations of the same: And with this paper, its learned writer has incorporated a communication, on the same subject, made to him by Mr. Rittenhouse.

Until about the period at which the latest of these favourite transactions of Mr. Rittenhouse took place—namely, his geometrical employment in ascertaining the Latitude and Longitude of Norriton and Philadelphia, respectively,—he continued to reside on his farm at Norriton. And here he still carried on, with the aid of some apprentices and journey-men, his self-acquired occupation of a Clock and Mathematical Instrument-maker: combining, at intervals, with these mechanical pursuits, an unceasing attention to his philosophical studies and researches; and occasionally employing himself, principally with a view to his health, in some of the occupations of Husbandry. Ever an economist of Time, of which he well knew the inestimable value, none of his hours which could be spared from necessary sleep were suffered to be unemployed. In this rural abode, he enjoyed the comforts of domestic life amidst his little family, consisting only of an amiable wife and two young children. In short, no part of his time was unengaged, or uselessly passed; although he, not unfrequently, felt the solace of friendly calls, and was gratified by visits from persons of science, worth, and distinction.

The writer of these memoirs designed to narrate those circumstances most worthy of notice, in the Life and character of Mr. Rittenhouse, in their chronological order; and this plan will be generally adhered to. Having followed our philosopher in his astronomical and mechanical pursuits, up to the year 1770, it therefore becomes proper to recur to a period of his life some few years earlier, in order to introduce the history of his Orrery, before mentioned; a piece of mechanism which is admitted, by all competent judges of its merit, to be one of the greatest of his works.

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Footnote 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.

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The Planetarium invented by Mr. George Graham,—and a model of which was improperly retained by Mr. Rowley, its constructor,—had, long before the appearance of Mr. Rittenhouse’s machine, acquired the name of an Orrery; in compliment to Richard Boyle, Earl of Orrery, who merely patronized the construction of one, from the artist Rowley’s pirated model. This complimentary appellation of Mr. Graham’s then newly invented Planetarium is said to have been bestowed upon it by Lord Orrery’s friend, Sir Richard Steele: and, the name being thus applied to that machine, all those of the nature of Planetaria, subsequently constructed,—however variant in usefulness or design, from the original one bearing the name of an “Orrery,”—were denominated Orreries. In compliance, then, with long established usage, Mr. Rittenhouse modestly called his Planetarian-machine, from the first projection of it, an Orrery; although the entire merit, both of the invention and construction, belonged to himself.

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Footnote 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.

Footnote 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.

Footnote 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.

Footnote 135:

Besides the Orrery here referred to, as the invention of the celebrated mechanic and watchmaker, Mr. George Graham, a like machine was afterwards contrived by Mr. James Ferguson, an eminent Scotch mechanic and astronomer, and another planetarium of the same kind, by Mr. William Jones, an ingenious mathematical instrument maker, of London. From the planetarium or orrery of Graham, however, as a model, all the modern orreries, prior to Mr. Rittenhouse’s, appear to have been taken. The one constructed by Mr. Rowley is said to be very similar to that invented by Dr. Stephen Hales.

But the idea of a planetarium, somewhat similar to the Rittenhouse-orrery, seems to have been conceived by Huygens, who died in 1695. A collection of this celebrated philosopher’s works was printed at Leyden in the year 1724 and 1728: and in these will be found the description of a planetarium; “a machine” (says Lalande, in speaking of the one contemplated by Huygens,) “which represents, by wheel-work, the revolutions of the planets around the sun and of the moon around the earth, in their durations and natural dimensions; with their excentricities, their inequalities, and their inclinations towards the ecliptic.” See Lalande’s Astron.

Footnote 136: