An epitome of astronomy, with the new discovered planets, and the late comet, as illustrated by the eidouranion; or, transparent orrery / originally invented by A. Walker, and as lectured upon by his son, D.F. Walker.

  • Adam Walker
Date:
1818
Catalogue details

Licence: Public Domain Mark

Credit: An epitome of astronomy, with the new discovered planets, and the late comet, as illustrated by the eidouranion; or, transparent orrery / originally invented by A. Walker, and as lectured upon by his son, D.F. Walker. Source: Wellcome Collection.

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    very sublime and simple provision for the otherwise long continued darkness which at opposite seasons of the yeai would envelope the polar regions of the Earth. If the Moon moved in the same plane with the Earth, there would be an eclipse every full and change ; but as she travels five degrees and three quarters to the North, and the same to the South of it, every lunation, she only crosses the plane of the Earth’s orbit in two places ; which points of intersection (called the Moon’s nodes) move nineteen degrees and three quarters towards the West every year, and therefore pass round the Heaven in 18 years and 225 days : which is the golden number of our calendar. Hence, when one of these nodes is between the Earth and the Sim at the change, the Moon’s shadow is thrown on the Earth, and she eclipses the Sun; and if she comes to the full when either node is-opposite to the Sun, she falls into the Earth’s shadow, and loses for a short time her borrowed light; but as she mostly passes above or below the Earth’s sha¬ dow, we have Eclipses very seldom. These phenomena are exhibited in the Eidou- ranion as they appear in nature, and are rendered perfectly intelligible to every capacity. N. B. Rotulas, exhibiting the Phase3, Eclipses, &c. of the Moon, and the rising and setting, &c* of the Stars, and by which
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