Part 31

The Schehallien is a mountain in Scotland, being one of the highest points in that range of mountains called the Grampian-Hills. The elevation of the Schehallien above the surface of the sea is about 1760 feet. W. B.

Footnote 122:

Mr. Vince observes, in his Complete System of Astronomy, (vol. i. p. 419) that the Transit of Venus affords a very accurate method of finding the place of the node; and this he verifies expressly by calculations founded on the observations made by Mr. Rittenhouse at Norriton, in the year 1769.

Footnote 123:

To so honourable a testimony, in favour of the merits of the Pennsylvania observers of this Transit, as that of Mr. Maskelyne, the acknowledgments of many other eminent foreign astronomers might be superadded: And the Rev. Dr. Smith, addressing himself to the American Philosophical Society, observes, “that societies of the first reputation in Europe are not ashamed to place our labours on a footing with their own; freely acknowledging, that we have been chiefly instrumental in ascertaining that great desideratum in astronomy, the sun’s parallax; and, consequently, the dimensions of the solar system.” See his Oration, delivered before the society, Jan. 22, 1773.

Footnote 124:

The compliment here paid by the Astronomer-Royal to the Hon. T. Penn, proprietary of the late province of Pennsylvania, for the zeal he manifested in promoting the Pennsylvania Observations of the Transit of Venus, was well merited,—as the detailed accounts of that highly interesting phænomenon abundantly shew.

Nor was that the only instance in which Mr. Penn discovered his attachment to the reputation and prosperity of that extensive American territory, which continues to bear the name of his family. He was, on various occasions, a liberal and disinterested benefactor to public institutions in Pennsylvania: as a proof of which, his aggregated donations to the College of Philadelphia, prior to the American war, amounting to about twelve thousand dollars—besides a grant of the manor of Perkessie in Bucks county, containing upwards of 3000 acres,—need alone be mentioned.

But it is within the knowledge of many persons in the midst of whom these memoirs are penned, that even the Juliana Library Company, in Lancaster (an inland and secondary town of Pennsylvania) experienced repeated proofs of the munificence of Mr. Penn, and also of his late truly noble and excellent consort, after whom that institution was named. The writer himself, well knows, from the tenor of numerous letters, not only from Mr. but Lady Juliana Penn, (who honoured the Rev. Mr. Barton with their friendship and correspondence, for the space of twenty years,—a patronage which was continued to a member of his family, long after Mr. Penn’s death,) the generous and unremitted attention of both, to whatever seemed likely to promote the honour or the interest of Pennsylvania.

Thomas Penn, Esq. died on the 21st of March, 1775, when he had just completed the seventy-fourth year of his age. He was the survivor of all the children of the illustrious founder of Pennsylvania; “whose virtues, as well as abilities, he inherited in an eminent degree,”—as was justly observed in an obituary notice published soon after his decease. Lady Juliana, his widow, survived him many years.

In the Pennsylvania Gazette (then published by Messrs. Hall and Sellers, but originally by Franklin and Hall,) for May 17, 1775, appeared the following just tribute to the memory of Mr. Penn.

“He had the principal direction of the affairs of this government for half a century, and saw such an increase of population, arts, and improvements in it, as during the like period, perhaps no man, before him, ever beheld in a country of his own. He rejoiced at the sight, was a kind landlord, and gave a liberal, often a magnificent encouragement, to our various public institutions. The Hospital, the College, our different Libraries and Religious Societies, can witness the truth of this: For he did not confine himself to sect or party; but, as became his station, and the genius of his father’s benevolent policy, he professed himself a friend to universal liberty, and extended his bounty to all. In short, as the grave, which generally stops the tongue of flattery, should open the mouth of Justice, we may be permitted to conclude his character by saying,—that he was both a great and a good man.”

The writer of these Memoirs hopes he will not be censured by any Pennsylvanian of generous feelings, for introducing, in the Appendix, some elegiac verses (by an unknown hand,) in commemoration of the virtues of this worthy man; who was not only a munificent benefactor to this country, and a bountiful patron of the Memorialist himself, as well as his family; but who, also, took a very friendly interest in the reputation and prosperity of Mr. Rittenhouse. These verses were published in The Pennsylvania Magazine, for Oct. 1775.

Footnote 125:

In addition to the honourable testimony of the Astronomer-Royal, in favour of the Pennsylvania Observers of the Transit of Venus, is the following eulogy of another eminent English astronomer,—as communicated by Dr. Franklin to Dr. T. Bond, one of the Vice-Presidents of the Philosophical Society, in a letter from London dated the 5th of Feb. 1772. The Rev. Mr. Ludlam, the gentleman referred to, and whom Dr. Franklin styles “a most learned man and ingenious mechanic”—in a paper published in the Gentleman’s Magazine (and a copy of which, subscribed by himself, was sent by him to the Society,) giving an account of the Society’s Transactions, more especially their Observations of the Transit of Venus,—applauds both the General Assembly and the late Proprietaries of Pennsylvania, for the countenance and assistance they gave to the making those Observations.——“No astronomers,” said Mr. Ludlam, “could better deserve all possible encouragement; whether we consider their care and diligence in making the Observations, their fidelity in relating what was done, or the clearness and accuracy of their reasonings on this curious and difficult subject.” He then mentions, in very honourable terms, the papers of Mr. Rittenhouse, Dr. Smith, Dr. Ewing, and Mr. Biddle, who drew up the several accounts of the Observations made at Norriton, Philadelphia, and Cape-Henlopen; and adds, that “they have very honestly given not only the Result of their Observations, but the Materials also, that others may examine and judge for themselves; an example worthy of imitation by those European astronomers, who are so very shy of giving particulars, and vouch for their Instruments and Observations in general terms.”

The same gentleman, in a letter dated at Leicester (in England,) January the 25th, 1772, and transmitted to the Philosophical Society by Dr. Franklin, wrote thus:—“The more I read the Transactions of your Society, the more I honour and esteem the members of it. There is not another Society in the world, that can boast of a member such as Mr. RITTENHOUSE: theorist enough to encounter the problems of determining (from a few Observations) the Orbit of a Comit; and also mechanic enough to make, with his own hands, an Equal-Altitude Instrument, a Transit-Telescope, and a Time-piece. I wish I was near enough to see his mechanical apparatus. I find he is engaged in making a curious Orrery. May I ask,” &c.

As further evidence of the high estimation in which the Transactions of the American Philosophical Society, and particularly of the Observers of the Transit, were held abroad, Dr. Wrangel, an eminent and learned Swedish clergyman, wrote thus to Dr. Smith from Stockholm, under the date of Oct. 18, 1771:—“I have been agreeably surprised to observe the rapid progress of your American Society, of which I esteem it a great honour to be counted a member,” &c.—“Your accurate Observations of the Transit of Venus have given infinite satisfaction to our (Swedish) astronomers; as will the rest of your Transactions, to the literary world, when they come to be further known.”

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Here the observation will emphatically apply;—Laus est, â viro laudato laudari.

Before this interesting occurrence in the life of Mr. Rittenhouse is finally passed over, the reader’s attention is solicited to the beautiful and animated description given by Dr. Rush, in his Eulogium, of the sensations which must have been more particularly experienced by that extraordinary man, on the near approach of the long-expected Phænomenon.—“We are naturally led here,” says the learned Professor, “to take a view of our Philosopher, with his associates, in their preparations to observe a phænomenon which had never been seen but twice before, by any inhabitant of our earth, which would never be seen again by any person then living, and on which depended very important astronomical consequences. The night before the long-expected day, was probably passed in a degree of solicitude which precluded sleep. How great must have been their joy, when they beheld the morning sun!—‘and the whole horizon without a cloud;’ for such is the description of the day, given by Mr. Rittenhouse, in the report referred to by Dr. Smith. In pensive silence and trembling anxiety, they waited for the predicted moment of observation: it came,—and brought with it all that had been wished for, and expected, by those who saw it.—In our Philosopher, it excited—in the instant of one of the contacts of the planet with the sun, an emotion of delight so exquisite and powerful, as to induce fainting. This,” then remarks Dr. Rush, “will readily be believed by those who have known the extent of that pleasure which attends the discovery, or first perception of Truth.”

Footnote 126:

According to Mr. Lalande, (in his Astronomie, vol. ii.) the transit of Venus over the Sun, in 1639, observed by only Messrs. Horrox and Crabtree, two Englishmen, and which was the first ever observed, was seen in consequence of a fortunate accidental circumstance. He says, that Horrox had been occupied in making calculations for an almanack, from the Tables of Lansbergius, which are much less perfect than the Rudolphine Tables: that these Tables of Lansbergius were in an error of 16′ for the latitude of Venus, while the Rudolphine Tables had an error of only 8′; but the one of Lansbergius made Venus pass on the sun in such a way, as that the transit ought to be visible; whereas the tables of Kepler represented the planet as passing below him; and thus it was, remarks Lalande, that bad tables occasioned a good observation. Relying on these tables, which Lansbergius had extolled with a confidence likely to produce imposition, Horrox prepared himself to observe that transit; and on the 24th of November, it took place at the time he expected, Venus being about half an hour on the sun when he set. He had sent on the occasion to his friend Crabtree, who was at Manchester, some miles from Hoole: and he observed the transit, likewise; though very imperfectly, by reason of intervening clouds. W. B.

On the 9th of November, following, there was a Transit of Mercury over the Sun. An account of this phænomenon,—as observed at Norriton by William Smith, d. d. John Lukens, Esq. and Messrs. David Rittenhouse and Owen Biddle, the Committee appointed for that Observation by the American Philosophical Society,—was drawn up and communicated to the Society, by direction and in behalf of the Committee, by Dr. Smith: this will be found in the first volume of the Society’s Transactions. In this report it is remarked, that—“the first time that ever Mercury was observed on the Sun’s disk, was by Gassendus at Paris, October 28th 1631, O. S. and that the Transit of Nov. 9th was the fourth in that class; the two intermediate ones, each at forty-six years distance, having been observed by Dr. Halley, in 1677 and 1723.”

Mr. Maskelyne, the celebrated English Astronomer before mentioned,—in a letter to Dr. Smith, of the 26th of December, 1769—expressed a wish “that the difference of Meridians of Norriton and Philadelphia, could be determined by some measures and bearings, within one-fiftieth or one-hundredth part of the whole; in order to connect,” continues Mr. Maskelyne, “your observations of the Longitude of Norriton with those made by Messrs. Mason and Dixon, in the course of measuring the degree of Latitude.”—This request of the Astronomer Royal was communicated to the Philosophical Society of Philadelphia; in consequence of which, Dr. Smith, Mr. Lukens and Mr. Rittenhouse, were appointed to make the terrestrial measurement required. These gentlemen, having taken to their assistance Mr. Archibald M’Clean and Mr. Jesse Lukens, two able and experienced Surveyors, commenced their operations at Norriton, early on the 2d day of July following, and completed their survey on the 4th day of that month. The Report of the able Committee, to which this business was assigned by the American Philosophical Society, is also contained in the first volume of the Transactions of that learned Body. After giving various calculations, resulting from the operations of that committee, the Reporter says—“Hence, by the above measurement and work, we get Norriton Observatory 52″ of time West of the Observatory in the State-house Square; which is exactly what we got by that excellent element, the external contact of Mercury with the Sun, Nov. 9th 1769.”—“The external contact,” continues the Reporter, “gave it something more; owing, no doubt, to the difference that will arise among Observers, in determining the exact moment when the thread of light is compleated: and the mean of all our Observations gives the difference of Meridians, between Norriton and Philadelphia, only 4″ of time more than the terrestrial measurement, and the external contact of Mercury, gave it,—which may be taken as a very great degree of exactness; if we consider that the difference of Meridians, between the long-established Observatories of Greenwich and Paris, (as Mr. De la Lande writes, Nov. 18th 1762,) was not then determined within 20″ of time—For, he says, ‘some called it 9′ 15″; others, 9′ 40″;’ but that he himself commonly used 9′ 20″, though he could not tell from what Observations it was deduced.—Finally, the Report fixes Philadelphia to be 5^h 0′ 37″, and Norriton, 5^h 1′ 29″ West from Greenwich. The Latitude of Norriton, as deduced from the actual mensuration just mentioned, connected with Observations previously made by Mr. Rittenhouse—predicated also, in part, on antecedent Calculations of Messrs. Mason and Dixon, who, (having been furnished with a complete Astronomical Sector,) had ascertained the southernmost point of the City of Philadelphia to be in Latitude 39° 56′ 29″,4. N.—is stated, in the same Report, as being 40° 9′ 31″. It came out, by the measurement, 25″.09 less North, with respect to the southernmost point of Philadelphia, than Mr. Rittenhouse’s Observations had given it; and, in making these, he had no better Instrument than Sisson’s two-and-an half feet Quadrant. Nevertheless, the framer of the Report remarks, “as both were fixed by celestial observations and experienced Men, the small difference ought perhaps to be divided; and if a mean be taken, to reconcile it with the terrestrial measure, the Lat. of the south point of Philadelphia would be 39° 56′ 42″; and that of Norriton, 40° 9′ 43″.

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Footnote 127:

Flamsted, Halley, Bradley and Bliss, successively occupied the royal observatory at Greenwich, from the time of its institution by Charles II.; and, in the year 1765, the last of these eminent men was succeeded in the place of Astronomer-Royal, by Nevil Maskelyne, B. D. a man who, in the words of the profound French astronomer, Lalande, “has sustained perfectly the reputation of that famous observatory.”

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.”