Astronomy Explained Upon Sir Isaac Newton's Principles: And made easy to those who have not studied mathematicsFerguson, James
Science
Astronomy Explained Upon Sir Isaac Newton's Principles: And made easy to those who have not studied mathematics
Ferguson, James
Astronomy -- Early works to 1800
+----------------------------------------------+-------------+------------+
| | Sun’s Long. | Sun’s mean |
| | from Aries. | Anomaly. |
| +-------------+------------+
| | s ° ʹ | s ° ʹ |
| Table I. To the Sun’s mean Place and +-------------+------------+
| Anomaly at the mean time of New Moon | | |
| in _March 1764_, N. S. | 11 17 7 | 8 2 23 |
| Add the same from Tab. VI. for one Lunation, | | |
| to carry it to _April_ | 0 29 6 | 0 29 6 |
| | --------- | ---------- |
| Mean Place and Anomaly at the time of New | | |
| Moon in _April_ | 0 10 13 | 9 1 29 |
| To which place add the Sun’s Equation | +------------+
| from Tab. XII. | 1 56 | Equal |
| | --------- | 1° 56ʹ |
| And it gives the Sun’s true place | 0 12 9 | Additive. |
| +-------------+------------+
| Which is Aries 12° 9ʹ; and this, when taken from three Signs, or the |
| beginning of Cancer, leaves 2 signs 17 deg. 51 min., or 77° 51ʹ for |
| the Sun’s distance from the then nearest Solstice. |
+-------------------------------------------------------------------------+
360. But because the Sun’s true Place is often wanted when the Moon is
neither New nor Full, we shall next shew how it may be found for any
given moment of time: though this be digressing from our present
purpose.
In Table XVI find the nearest lesser year to that in which the Sun’s
Place is sought; and take out the Sun’s mean Longitude and Anomaly
answering thereto; to which add his mean motion and Anomaly for the
compleat residue of the years, with the month, day, hour, and minute,
all taken from the same Table, and you have the Sun’s mean Longitude and
Anomaly for the given time. Then, from Table XII take out the Sun’s
Equation by means of his Anomaly (making proportions for the odd minutes
of Anomaly) which Equation being added to or subtracted from the Sun’s
mean Longitude from Aries, as the titles in the Table direct, gives his
true Place, or Longitude from the beginning of Aries, reckoned according
to the order of the Signs § 354.
EXAMPLE.
_To find the Sun’s true Place_ April _30th, A. D. 1757, at 18 minutes 40
seconds past 10 in the morning_.
Public-domain text, read in full here on John Shaqi.
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