Stars and telescopes; a hand-book of popular astronomy founded on the 9th ed. of Lynn's Celestial motions (1901)
Todd, David P. (David Peck), 1855-1939, Lynn, William Thynne, 1835-1911 · Boston, Little, Brown · leaf 372
TYPICAL GREAT TELESCOPE OF THE I7TH CENTURY{Built ami used by Hevbuus at Danlzig) In the telescopes of Galileo and Huygens and alltheir followers for about a century, the image of aremote object was formed by a single lens of doubleconvexity. The glass was full of imperfections ; butbesides this,… … colored fringes, so that a limit to the effective size otthe telescope seemed to be set by the laws of natureherself. But it was soon found that the disturbingcolor effects were minimized, if the lens was groundvery flat. This, however, necessitated great focallength, and many telescopes were built…
Astronomy
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
