Annals Volume N . 1

Annals Volume N . 1

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1866 edition. Excerpt: ...By means of movable adjustments we can set the machine (having our sheet ruled for Eight Ascension and Declination), so that it will give the position of the zone, at the beginning of the year, without sensible error. For adjusting in Eight Ascension, the cylinder can be moved about its axis, being held in position by a friction block. For the declination, we lengthen or shorten the rod (/), by means of the screw (x), fig. 2. The scale for declination can be varied at pleasure, by changing the position of the connecting rod (/), on the lever I, fig. 1. This apparatus can be adapted to any Telescope either transit or equatorial; neither does its use interfere with the ordinary work for exact positions. In the observation of Asteroids on the meridian, a great deal of time is wasted, especially when the error of the Ephemeris is considerable. And even when the error is only 2' or 3' in declination, in certain portions of the heavens, it is almost impossible to rind the body with a meridian instrument. This apparatus affords great facility in finding these bodies, when we have an approximate Ephemeris; since it is only necessary to observe, on two nights, a short zone of five minutes in Eight Ascension and 10 minutes in Declination. The comparison of these two charts will at once show which is the planet, provided it is included within those limits; when, the Ephemeris being corrected, it can be observed on the meridian in the usual way. This has been thoroughly tested in finding the old Asteroids, where the error of the Ephemeris has been considerable. In our ordinary work, as we observe all stars visible, the limit being 13-14 magnitude, it is usually impracticable to observe a zone of greater width than 10' or 12', and within these limits it is...show more

Product details

  • Paperback | 70 pages
  • 189 x 246 x 4mm | 141g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123663103X
  • 9781236631039