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
s ° ʹ
Sun’s mean distance from the Node at F. Moon in _May 1761_ 11 26 47
Add the Equation of the Node, for the Sun’s Anomaly 10^s
18° 15ʹ[85] + 6
--------
Sun’s mean distance from the Node corrected 11 26 53
Add the Equation of the Sun’s mean Place + 1 15
--------
Sun’s true distance from the Ascending Node 11 28 8
To which add 6 Signs, See § 363 6
--------
The sum is the Moon’s true distance from the same Node 5 28 8
[Sidenote: Pl. XII.]
Or the _Argument_ of her _Latitude_; which in Table XIV, gives the
Moon’s true Latitude, _viz._ 9ʹ 56ʺ North Descending.
385. Having by the foregoing precepts § 355 found the true time of
Opposition of the Sun and Moon in a lunar Eclipse, with the Moon’s
Anomaly enter Table XV and take out her horizontal Parallax, also her
true horary Motion and Semi-diameter: and likewise those of the Sun by
his Anomaly, as already taught § 364 & _seq._ Then add the Sun’s
horizontal Parallax, which is always 10 Seconds, to the Moon’s
horizontal Parallax, and from their sum subtract the Sun’s
Semi-diameter; the remainder will be the Semi-diameter of that part of
the Earth’s shadow which the Moon goes through.
386. From the Sum of the Semi-diameters of the Moon and Earth’s Shadow,
subtract the Moon’s Latitude; the remainder is the parts deficient.
Then, as the Semi-diameter of the Moon is to 6 Digits, so are the parts
deficient to the Digits eclipsed.
387. If the parts deficient be more than the Moon’s Diameter, the
Eclipse will be total with continuance; if less, it will not be total;
if equal, it will be total, but without continuance.
388. Now collect the Elements for projecting this Eclipse.
ʹ ʺ
Moon’s horizontal Parallax 55 32
Sun’s horizontal Parallax (always) 10
The Sum of both Parallaxes 55 42
From which subtract the Sun’s Semi-diameter 15 54
Remains the Semi-diameter of the Earth’s Shadow 39 48
Semidiameter of the Moon 15 2
Sum of the two last 54 50
Moon’s Latitude subtract 9 56
Remains the parts deficient 45 0
Moon’s horary motion 30 46
Sun’s horary motion subtract 2 24
Remains the Moon’s horary motion from the Sun 28 22
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account