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 #:
000166
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 151 forms of single-mirror heliostats. In fig. 79, for example, the position arm B-F can be raised or lowered and the entire arm can be rotated around the column A. When the light is accurately directed, all the clamps can be tightened and the clock-work should cause the mirror to hold the light constantly in position. It will be found much easier to center the light on one axis if the heliostat is at about the same level as the condenser and objective. This position can be secured by raising the heliostat or the lantern, whichever is more convenient, provided the two are not on the same level to start with. o FIG. 80. PRINCIPLE OF THE UNIVERSAL HELIOSTAT SHOWN IN FIG. 79. O A The clock arm pointing directly towards the sun. 0 B The position arm, pointing in the direction in which it is desired to reflect the light. in The incident light parallel to 0 A. rf The reflected light. A B The mirror. The mirror is perpendicular to the plane passing through A , 0 and B. 0 N Perpendicular to the mirror A B. In order to prove that incident light parallel to A 0 will be reflected from the mirror parallel to 0 B it is necessary to prove that A O, 0 B and 0 N are in the same plane and that O N bisects the angle A 0 B. The mirror being perpendicular to the plane containing A , 0 and B and the line O N perpendicular to A B must also be in this same plane. The triangle A O B is isosceles by construction, as A O and 0 B are made equal, hence the perpendicular to the base must bisect the vertex angle.