. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. y also be used with stillbetter results as the images will be still further separated. LIGHT. 127 POLARIZATION OF LIGHT. Plane-polarized light may be obtained in greatquantity by using for a reflector in the porte lumierea plate of glass blackened upon its back a piece of good window-glass, without bubblesor striae, and paint it upon one side with lamp-blackmixe4 in Japan varnish. It will be best to lay on twoor three coats in order to comple
. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. y also be used with stillbetter results as the images will be still further separated. LIGHT. 127 POLARIZATION OF LIGHT. Plane-polarized light may be obtained in greatquantity by using for a reflector in the porte lumierea plate of glass blackened upon its back a piece of good window-glass, without bubblesor striae, and paint it upon one side with lamp-blackmixe4 in Japan varnish. It will be best to lay on twoor three coats in order to completely cover the it between the eye and the sun, and all theuncovered and thin places can be seen; they shouldreceive another coat of paint. This painted glassshould be of the same size as the plane mirror in theporte lumiere^ upon which it may now be placed andfastened by tying about them both a thread or stretchinga ring of elastic cord over them. If the beam of lightwhich is now reflected from the unpainted surface ofthis glass is sent through a double-convex lens andthen received upon the screen, it will be seen to be. Fig, 95. much less intense than the beam from the silveredmirror, but some of the most attractive experiments inthe whole domain of physics are possible with thislight. A Nicols prism n will be necessary, and the largerit is the better, but very good effects may be obtained 128 THE ART OF PROJECTING. with such small ones as come with the polarizingattachment to common microscopes. With one havinga face three-quarters of an inch upon a side, everythingessential can be shown to a large audience. 1. Place the prism at the focus of the lens so thatall the light will pass through it. Now, if the prism berotated upon the beam as an axis, the disk of light uponthe screen will decrease in brightness until it is nearlyor quite invisible; and if the prism be turned stillfurther in the same direction the light will reappearand attain its maximum brightness w
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherbosto, bookyear1877
