The practical astronomer : comprising illustrations of light and colours, practical descriptions of all kinds of telescopes, the use of the equatorial-transit, circular, and other astronomical instruments, a particular account of the Earl of Rosse's large telescopes, and other topics connected with astronomy (1845)
Dick, Thomas, 1774-1857 · London : Seeley, Burnside, and Seeley · leaf 251
this tube, s aleaden bullet, and t a spool to wind the threadon ; u is pins for the thread to pass through ; x therest for the observer to lean upon, and y the lan-tern. Fig. 46 is an apparatus contrived by M. dela Hire for managing the object-glass; but whichit would be too tedious particularly to… … And to find an object more readily, a broad annu-lus of white pasteboard was put over the tubethat carried the eye-glass ; upon which the imageof the object being painted, an assistant whoperceived it, might direct the tube of the eye-glassinto its place. Such was the construction of the telescopes…
Astronomy · Astronomical instruments · Telescopes
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