Stars and telescopes; a hand-book of popular astronomy, founded on the 9th ed. of Lynn's Celestial motions (1899)
Todd, David P. (David Peck), 1855-1939, Lynn, William Thynne, 1835-1911. Celestial motions · Boston, Little, Brown and company · leaf 386
erimentshad satisfied him that a lens of short focal lengthcould never be made to yield an optically perfect Telescopes and Houses for Them 327 image, Euler (page 96) doubted the accuracy ofthis conclusion, and suggested that a combination oflenses of glass and water, of suitable curvatures,… … COURSE OF RAYS THROUGH TELESCOPE{Objective A forms image of object at B) cave lens of flint glass with the original convex lensof crown glass. Flint glass contains much oxideof lead and is very dense, and its power of dispersinga beam of white light is about double that of anequal prism of crown…
Astronomy
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