Astronomia Britannica exhibiting the doctrine of the sphere, and theory of the planets decimally by trigonometry, and by tables : fitted for the meridian of London ... / by John Newton ...

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Title: Astronomia Britannica exhibiting the doctrine of the sphere, and theory of the planets decimally by trigonometry, and by tables : fitted for the meridian of London ... / by John Newton ...
Author: Newton, John, 1622-1678.
Publication: London :: Printed for the author by R. and W. Leybourn, and are to be sold by Thomas Piercepoint ...,; 1657.
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Subject terms: Astronomy -- Early works to 1800.; Planetary theory -- Early works to 1800.; Astronomy -- Mathematics -- Early works to 1800.
Link to this Item: http://name.umdl.umich.edu/A52255.0001.001
Cite this Item: "Astronomia Britannica exhibiting the doctrine of the sphere, and theory of the planets decimally by trigonometry, and by tables : fitted for the meridian of London ... / by John Newton ..." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A52255.0001.001. University of Michigan Library Digital Collections. Accessed June 4, 2024.

Pages

CHAP. 24. To find the Quantity of a Lunar Ecclipse.

BY the true motion of the Moons Latitude, find her true latitude, according to the former directions: this in our example is 0. 51496 North Descendant.

2 Find out the Semidiameter of the Moon by her meane ano∣maly out of the Table, as also h•••• Horizontall parallax; and with the meane anomaly of the Sun, take out the Semiangle of the Cone of the shadow; and this subtract from the Moons Horizontall parallax, there rests the Semid. of shaddow.

3 Adde together the Semidiameter of the shadow, and Semidiameter of the Moon, and from the summe subtract the Latitude of the Moon, the remainder is the scruples of the Moons diameter ecclipsed.

Page 155

Example.

Horizontall parallax of the Moon: . 94409
Semiangle of the Cone Subt.: . 23455
Semidiameter of the shaddow: . 70954
Semidia meter of the Moon: . 26431
Summe of the Semidiameters: . 97385
Latitud•• of the Moon, Subt.: . 51496
Scruples deficient: . 45889

4 Convert these Scruples into digits or parts, whereof the Moones body containes 12, thus,

As the Moones diameter 52862 co. ar.: 5. 276857
Is to the Scruples deficient 45889: 4. 661708
So is 12 digits: 1. 079181
To the digits ecclipsed 10. 417: 1. 017746

Yet note that Lunar Eclipses are of three sorts.

1 Partiall, when the Scruples deficient are lesse then the diameter.
2 Totall without continuance when they are equall.
3 Totall with continuance when the scruples deficient are greater then the diameter, and in these the digits eclipsed are more then 12, which are so to be understood, as that they shew how far the ecclipse is over the body of the Moon.