Optical projection: a treatise on the use of the lantern in exhibition and scientific demonstration (1906)

Record Details:

Title:
Optical projection: a treatise on the use of the lantern in exhibition and scientific demonstration
Date:
1906
Author:
Wright, Lewis, 1838-1905
Publisher:
London, New York, Bombay : Longmans, Green and Co.
Volume:
Optical projection: a treatise on the use of the lantern in exhibition and scientific demonstration
Leaf #:
00049
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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34 OPTICAL PROJECTION length, which is best as a single tube, but may be a double sliding one as shown in the figure. In the first case the whole .7 ^ is perfectly rigid, and per- fectly simple ; and lengthening tubes may either be ordered with the original apparatus, r~ or, if suddenly called for by FIG 21—Ada ter some extraordinary occasion, could be fitted in all large towns in a few hours, by any working optician worthy of the name. This method of construction is being gradually adopted by most of the lantern-makers who really have much experi- ence with the instrument. CHAPTER III THE RADIANT THE qualities desired in the radiant are brilliance and \\hiteness of light, and that this light be concentrated into as small a space as possible. The perfect radiant would be an intensely luminous point, which would give the most equal illumination and the best definition. The radiants used in practice by no means come up to this ideal. They comprise (1) fatty oil lamps, (2) petroleum oil lamps, (8) gas-burners, (4) the lime-light in its various forms, and (5) the electric light. 19. Fatty Oil Lamps.—Except in small toy lanterns, it is seldom we now find these lamps employed; but for many years they were the only radiants used at all, even in public exhibitions of dissolving views. With hand-painted trans- parent slides they did good work, too ; giving usually discs of eight feet diameter on transparent screens. They will not