The description and use of the globes, and the orrery. To which is prefix'd by way of introduction, a brief account of the solar system ... To which is added ... an appendix containing the description ... of the armillary sphere / by Joseph Harris.

  • John Harris
Date:
1773
Catalogue details

Licence: Public Domain Mark

Credit: The description and use of the globes, and the orrery. To which is prefix'd by way of introduction, a brief account of the solar system ... To which is added ... an appendix containing the description ... of the armillary sphere / by Joseph Harris. Source: Wellcome Collection.

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    parallel, and at their proper diftance from the equinodtial. On the North¬ ern half of the ecliptic is a brafs femi- circle, moveable upon two points fixed in nr* and &: This femicircle ferves as a moveable horizon, to be put to any de¬ gree of latitude upon the North part of the meridian. The whole machine is alfo fo contrived, as to be fet to] any la¬ titude, without in the leaft affedting any of the infide motions: For this purpofe there are two ftrong hinges (N° 13,) fixed to the bottom frame, upon which the inftrument moves, and a ftrong brafs arch, having holes at every degree, thro’ which a ftrong pin is to he put, according to the elevation. This arch, and the two hinges, fupport the whole machine, when it is lifted up according to any latitude; and the arch at other times lies conveniently under the hot- tom frame. . When the machine,is fet to any la¬ titude (which is eafily done by two men, each taking hold of two handles, con-, veniently fixed for that purpofe) fet the moveable horizon to the fame degree upon the meridian, and you may form an idea of the refpedive altitude, or de~ preffions of the Planets, above or below , 1 N 2 the