Description and use of a new constructed equatorial telescope or portable observatory / made by E. Nairne.

  • Nairne, Edward, 1726-1806
Date:
1771
Catalogue details

Licence: Public Domain Mark

Credit: Description and use of a new constructed equatorial telescope or portable observatory / made by E. Nairne. Source: Wellcome Collection.

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    thereto, and upon the declination femicircle its de¬ clination. In order to have the other ufes of this inftrument, you mud: fet it to the hour XII on the equatorial plate, and to o on the femicircle of de¬ clination, and fet the axis E perpendicular to the horizon, and then this inftrument becomes an Equal Altitude Inftrument, a Tranfit Inftrument, a Theo¬ dolite, a Quadrant, an Azimuth Inftrument, and a Level; the manner of applying it to thefe different purpofes is obvious. The following is one Example of its Ufes in finding the Altitude of any ObjeTt. Set o of the femicircle of declination, to agree with o of its vernier index, and fallen it there; fix likewife the vernier of the equatorial plate to 12 o’clock, or o degrees; then, having fet the axis E per¬ pendicular, by means of the level F, turn the inftru¬ ment about horizontally upon the axis E, and verti¬ cally upon the axis of motion of the equatorial plate, until the objed appears in the middle of the field; and the index I will point out upon the quadrant G, the zenith diftance of the objed, the comple¬ ment of which to 90° is its altitude; hence the great- eft or meridian altitude may be found, from which the latitude of the place may be deduced in the ufuai manner. THE E N Do