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
“In order to know the true situation of a Planet at any particular time,
the small set of balls are to be put each on its respective axis; then
the winch to be turned round until each index points to the given time.
Then a small telescope, made for the purpose, is to be applied to the
central ball; and directing it to the planet, its longitude and
inclination will be seen on a large brass circle, silvered, and properly
graduated, representing the zodiac, and having a motion of one degree in
seventy-two years, agreeable to the precession of the equinoxes. So,
likewise, by applying the telescope to the ball representing the earth,
and directing it to any planet,—then will both the longitude and
latitude of that planet be pointed out (by an index and graduated
circle,) as seen from the earth.
“The two lesser faces are four feet in height, and two feet three inches
in breadth. One of them will exhibit all the appearances of Jupiter and
his Satellites—their eclipses, transits, and inclinations; likewise, all
the appearances of Saturn, with his ring and satellites. And the other
will represent all the phænomena of the moon, particularly, the exact
time, quantity, and duration of her eclipses—and those of the sun,
occasioned by her interposition; with a most curious contrivance for
exhibiting the appearance of a solar eclipse, at any particular place on
the earth: likewise, the true place of the moon in the signs, with her
latitude, and the place of her apoge in the nodes; the sun’s
declination, equation of time &c. It must be understood, that all these
motions are to correspond exactly, with the celestial motions; and not
to differ several degrees from the truth, in a few revolutions, as is
common in Orreries.
“If it shall be thought proper, the whole is to be adapted to, and kept
in motion by, a strong pendulum-clock; nevertheless, at liberty to be
turned by the winch, and adjusted to any time, past or future.”
“N. B. The diurnal motions of such planets as have been discovered to
revolve on their own axes, are likewise to be properly represented; both
with regard to the Times, and the situation of their Poles.”
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Public-domain text, read in full here on John Shaqi.
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