cture and screen, to prevent the image from being eitherupside down or right side to left. Second, the original picturemust be illuminated from the front, since transmitted light is outof the question, and this makes it difficult to get the illumina-tion strong enough. The projection lens L must be… … PROJECTION LANTERNS 10!) amount of light by using large carbons and a very heavy cur-rent, and the condenser system is made to cover a very largeangle from the arc. Usually a glass cell containing water isinterposed, to cut out much of the infrared light, which wouldunduly heat the picture. For use…
Light
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