Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures (1914)

Record Details:

Title:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures
Date:
1914
Author:
Gage, Simon Henry, 1851-1946
Publisher:
Ithaca, N.Y. : Comstock Publishing Co.
Volume:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures
Leaf #:
000154
Language:
English
Format:
Books
Contributor:
Gerstein - University of Toronto
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
Bibliography: p. 693-703
Date Added:
July 19, 2022
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CH. VI] HELIOSTATS FOR THE MAGIC LANTERN 139 § 233. Heliostat. — From the rotation of the earth on its axis from west to east the sun seems to move over the face of the sky \ FIG. 74. MAGIC LANTERN WITH SUNLIGHT. 5 Sunlight. Mirror The plane mirror serving to direct the sunlight horizontally into the condenser. Condenser The single plano-convex lens serving to converge the parallel beam of sunlight. (Compare the second element of the condenser in fig. 2). Ls Lantern slide. Objective The projection objective for projecting an image upon the white screen. The projection objective and the condenser should be of approximately the same focus. c Center of the projection objective where the rays from the condenser should cross. Axis Axis The principal optic axis of the condenser and of the projection objective. Screen Image The image of the lantern slide upcn the white screen. The apparent diameter of the sun's disc is 32'36" in midwinter and 31' 32" in midsummer, or it averages 32' 04" (Abbot, The Sun, p. 3; Ball's Astronomy, p. 127). The apparent area of the sun's disc at a distance of one meter is determined as follows: Its diameter is 32'o4" or .5343°. One centimeter at a distance of one meter subtends an angle of .573°, hence at one meter the sun's disc would appear to have a diameter of i = .933 centimeters. The area of such a •573 circle is : ' \ IT = .684 square centimeters. 4 . . .,.,,. Candle-power 1 he intrinsic brilliancy is then, Area 288,000 = in round num .684 bcrs, 421,000 candle-power per square centimeter or 2,720,000 candle-power per square inch.