A Compleat System of Opticks in Four Books, Viz; A Popular, a Mathematical, a Mechanical, and a Philosophical Treatise. to Which Are Added Remarks Upon the Whole Volume 2

A Compleat System of Opticks in Four Books, Viz; A Popular, a Mathematical, a Mechanical, and a Philosophical Treatise. to Which Are Added Remarks Upon the Whole Volume 2

By (author) 

List price: US$22.40

Currently unavailable

Add to wishlist

AbeBooks may have this title (opens in new window).

Try AbeBooks

Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1738 edition. Excerpt: ... While an index r s fixt to the board kl, pointed.tothe divisions of the wheel. 1202. Things being thus prepared, while the wheel pqr was-gentlzfi turned, the part of the wire near b, which played against the transverse plate fig, was viewed through a double microscope tu, till"the little hole in this plate appeared to be bisected by the wire. The telescope being thusz-z rectified immediately before the beginning of every observation of the transit of 7 Draconis, (which passes very near the zenith of Kew, ) and._ the division of the wheel over against-the index rs being then noted, the.wheel was turned again, till the intersection of the wires in the focus wass brought to touch the star at the instant of its transit. Then by the number of the revolutions of the wheel and the parts of arevolution that hadi passed by the fixtindex rs, the angular motion of the axis of the telescope was easily collected, from a proper table of minutesand seconds answer-ing to those revolutions. Now the differences of these angles foundat different observations, are the differences of the star's declination. And the _ instrument being rectified every time as above, it is easy to understand: that these angular difierences could not be altered-by any warping, shrinking or swelling of the materials of the instrument. 1203. Mr. Bradley's instrument has the addition of a divided arch of I 12 g degrees in the place of the platefg; and though its radius is but 12- all the trials he has made, that when it. is carefully rectified as above, its.. 2. Huglmsiu: gives us the following history of the discovery of this law I. " The refraction of rays at the surfaces of transparent bodies, is a thing taken notice of by the ancicnts. For Ari stgt/e has a...show more

Product details

  • Paperback | 84 pages
  • 189 x 246 x 4mm | 168g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236783751
  • 9781236783752