Astronomy explained upon Sir Isaac Newton's principles. And made easy to those who have not studied mathematics / To which are added, a plain method of finding the distances of all the planets from the sun, by the transit of Venus over the sun's disc, in the year 1761. An account of Mr. Horrox's observation of the transit of Venus in the year 1639; and, of the distances of all the planets from the sun, as deduced from observations of the transit in the year 1761. By James Ferguson.

  • James Ferguson
Date:
1770
Catalogue details

Licence: Public Domain Mark

Credit: Astronomy explained upon Sir Isaac Newton's principles. And made easy to those who have not studied mathematics / To which are added, a plain method of finding the distances of all the planets from the sun, by the transit of Venus over the sun's disc, in the year 1761. An account of Mr. Horrox's observation of the transit of Venus in the year 1639; and, of the distances of all the planets from the sun, as deduced from observations of the transit in the year 1761. By James Ferguson. Source: Wellcome Collection.

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    The Axes of the Pla- nets, what, Their Or- bits are not inthe fame plane with the Ecliptic. Syftem. All the Planets, as feen from him, move the fame way, and according to the order of Signs in the graduated Circle ¥ ¥ a o &c. which repre- {ents the great Ecliptic in the Heavens: but, as feen from any one Planet, the reft appear fome- times to go backward, fometimes forward, and fometimes to ftand ftill ;- not in circles nor ellipfes, but in * looped curves which never return into themielves. The Comets come from all parts. of the Heavens, and move in all forts of dire¢tions. 19. Eiaving mentioned the Sun’s turning round his axis, and as there-will be frequent occafion to {peak of the like motion of the Earth and other Planets, it is proper here to.inform the young Tyro in Aftronomy, that neither the Sun nor Planets have material axes to turn upon, and fupport them, as in the little imperfeét Machines contrived to reprefent them. For the axis of a Planet is 4 line conceived to be drawn through it’s center, about which it revolves as on a real axis. . The extre- - mities of this line, terminating in oppofite points of the Planet’s furface, are called it’s Poles. That which points towards the northern part of the — Ficavens, is called the North Pole; and the other, pointing towards the fouthern part, is called the Soul Pole. A bowl whirled from one’s hand into. the cpen air turns round fuch a line within itfelf, whilft it moves forward; and fuch are the lines — we mean, when we fpeak of the Axes of the Fieavenly bodies. 48 ne] 20. Let us {uppofe the Earth’s Orbit to be a . thin, even, folid plane; cutting the Sun through ~ Fleavens, where it will mark the great Circle called the Echiptic. This Circle we fuppote to be divided 39 equal parts, called Degrees ;” each Degree into 60 equal parts, called Minutes, and every Minute * As reprefented in Plate I, Fig, I. and deferibed § 138. | into 7