The elements of astronomy; a textbook . light of the sun are so intense that we cannotlook directly at it with a telescope as we do at the moon. A very convenient method of exhibiting the sun to a numberof persons at once is simply to attach to a small telescope aframe carrying a screen of white paper at a distance of a footor more from the eye-piece, as shown in Fig. 44. With aproper adjustment of the focus, a distinct image is formed onthe screen, which shows the main features very fairly; indeedwith proper precautions, almost as well as the most elaborate §182] PHOTOGRAPHY. 121 apparatus. S
The elements of astronomy; a textbook . light of the sun are so intense that we cannotlook directly at it with a telescope as we do at the moon. A very convenient method of exhibiting the sun to a numberof persons at once is simply to attach to a small telescope aframe carrying a screen of white paper at a distance of a footor more from the eye-piece, as shown in Fig. 44. With aproper adjustment of the focus, a distinct image is formed onthe screen, which shows the main features very fairly; indeedwith proper precautions, almost as well as the most elaborate §182] PHOTOGRAPHY. 121 apparatus. Still, it is generally more satisfactory to look atthe sun directly with a suitable eye-piece. With a small tele-scope, not more than 2\ or 3 inchesin diameter, it is usual to intro-duce a simple shade-glass betweenthe eye-piece and the eye, but thedark glass soon becomes very hotand is apt to crack. With largerinstruments it is necessary to useeye-pieces specially designed forthe purpose, and known as solareye-pieces, or Fig. 44. — Telescope and Screen.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjec, booksubjectastronomy
