Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 41
n principle this is thesame with the Gregorian ; but the small mirror, R, is con-vex, and is placed inside the focus, F, so that the rays arereflected from it before reaching the focus, and no imageis formed until they reach the opening in the large mirror.This form has an advantage over the… … Optically these forms of telescope are inferior to theNewtonian ; but the latter is subject to the inconvenience,that the observer must be stationed at the upper end ofthe telescope, where he looks into an eye-piece screwedinto the side of the tube. ASTRONOMY. 25 ()n the other hand, the…
Astronomy
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