Memoirs of the life of David Rittenhouse, LLD. F.R.S., late president of the American Philosophical Society, &c. : $b interspersed with various notices of many distinguished men : with an appendix, containing sundry philosophical and other papers, most of which have not hitherto been publishedBarton, William
History
Memoirs of the life of David Rittenhouse, LLD. F.R.S., late president of the American Philosophical Society, &c. : $b interspersed with various notices of many distinguished men : with an appendix, containing sundry philosophical and other papers, most of which have not hitherto been published
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″.[130]
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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.”
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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