The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular (1877)

Record Details:

Title:
The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular
Date:
1877
Publisher:
Philadelphia, J. A. Moore
Volume:
The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular
Leaf #:
00034
Language:
English
Collection:
Books
Format:
Books
Contributor:
University of California Libraries
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
Date Added:
July 19, 2022
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SOIOPTICON MANUAL. of radiation would lose intensity with distance, and so a lens of short focus, being nearer, would bring more light Fig. 14. to bear on the image. But the light in fact proceeds from I, and what passes through the condenser and picture becomes a cone of light, with its apex in the objective. This cone of light must be regulated by the position or power of the condenser so as to fall within the compass of the objective. Except for some reflections from the surfaces of the glasses, the light would not illuminate the room at all in its passage, and there would not be even the small need there is of the hood t (Fig. 15). ADVANTAGES OF A CONCENTRATED EIGHT. Could the light proceed from a mathematical point behind a faultless condenser, the pencils a! V d (Fig. 14) would be without marginal rays, and there would be nothing for the objective to do, for its office is to bring the marginal rays of each pencil to coincide with the axial ray. Were we to adjust the aperture of our window shutter (Fig. 1), to the apex of the cone, there would be no rays for the shutter to cut off. The imago would be formed anywhere within reach of the light, either with or without lens or stop. But in reality even the most concentrated light occupies some space with countless radiant points, so near together however that S