Analysis of a course of lectures on natural and experimental philosophy. Viz. 1. Magnetism, 2. Mechanics, 3. Chemistry, 4 & 5. Pneumatics, 6. Hydrostatics, 7. Electricity, 8. Fortification, 9. Optics, 10. Use of the globes, & c. 11 and 12. Astronomy / by A. Walker.

  • Walker, A. (Adam), 1730 or 1731-1821.
Date:
[1790]
Catalogue details

Licence: Public Domain Mark

Credit: Analysis of a course of lectures on natural and experimental philosophy. Viz. 1. Magnetism, 2. Mechanics, 3. Chemistry, 4 & 5. Pneumatics, 6. Hydrostatics, 7. Electricity, 8. Fortification, 9. Optics, 10. Use of the globes, & c. 11 and 12. Astronomy / by A. Walker. Source: Wellcome Collection.

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    [ 3^ ] but as (he mud then rife about noon9 that rifing' is not ta~- ken notice of. In fipring the moon is in them about her change, but as (he then gives no-light, her rifing is alfo urn- noticed. In Jummer {he rifes in Pi fees and Aries, about her third quarter, but at twelve o clock at night, confe- quently the phenomenon is feldom then regarded ; but in autumn thofe figns are oppofite to the fun, and therefore the moon muld be full in them, and, very ufefully for the farmers, rifes in their harveft immediately after fun- fet for feveral evenings together, and thence acquires the name of the harveft moon. (Proved by. the* Orrery and Globe.) » LECTURE XII. A S T R 0 N O M r. *TpILE planets are retained in their orbits by the power of gravity *—but as the fun is by far the larged body in our fydem, if no other power adted on them they would be drawn down to the funAll bodies therefore that move in curves, as the planets do round the fun, mud be adted upon by two principles; and motion being rectilineal, we fuppofe the Almighty gave each planet this kind of impulfe at its creation, fo that between one power drawing to the centre, and another acting perpendicular to itthe planets are impelled in eliptic orbits round the fun, as a pebble tied to a mill-done, and thrown from the hand, would re- i • / volve round the mill-done. An idea of this is given by a ball impelled fingly in a fquare in two diredtions, one per¬ pendicular to the other ; when both udt they give the du agonal of the fquare, &c. Our fydem mud be conceived as within the concave fphere feeming to be formed by the fixedftars, and the fun as near the centre of it, an huge globe of fire, near a mil¬ lion of miles in diameter, and near too millions of miles from