Astronomy, a handy manual for students and others (1918)
Dyson, Frank Watson, Sir, 1868-1939 · New York, E.P. Dutton & Co. · leaf 79
r. If the rays which passthrough F be intercepted by a second lens L, they canbe again converted into a parallel beam of light. Ifthe diameter of the second beam is no wider than thepupil of the eye, all the stars light which fell on thelens L passes into the eye. The telescope, in effect,supplies… … Diag. XXXVII. through F will be converted into a beam of parallelrays which, falling on the eye, will enable the star tobe seen. Similarly the cone of rays through G willbe converted into a parallel beam. The first beam isin a direction parallel to DF, and the second oneparallel to DG. Thus the eye…
Astronomy
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