. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. ll heated body at a. Theair that is heated in its neighborhood will so deflectthe rays of light as to make quite a fine appearanceof heat upon the screen. An alcohol lamp lightedand held there will have its whole projection uponthe screen: the lamp and flame in outline shadow,while the heated gases rising make an interestingpicture. To present a still more striking case, project a largesolar spectrum, as described on another page, and abouthalf-way between
. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. ll heated body at a. Theair that is heated in its neighborhood will so deflectthe rays of light as to make quite a fine appearanceof heat upon the screen. An alcohol lamp lightedand held there will have its whole projection uponthe screen: the lamp and flame in outline shadow,while the heated gases rising make an interestingpicture. To present a still more striking case, project a largesolar spectrum, as described on another page, and abouthalf-way between the prism and the screen hold thelighted alcohol lamp, moving it slowly along in thedifferent colors of the spectrum. 4 — Lenses. The refractive power of difTerent forms of lensesmay be shown by holding them in the beam ofparallel rays. The refractive power of a lens ofwater is seen by taking twowatch glasses or one watch glass,and a piece of plain glass a littlelarger, and bringing the two to-gether under the surface of space between these will bequite filled and they will adheretightly enough for the experi-ment. The same thing will also be exhibited by placing awatch glass upon the upper ring of the vertical attach- lOO THE ART OF PROJECTING. ment (Fig. 27). When water is poured in to fill it,the light will be refracted and an object may be pro-jected with it as with any other lens.
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherbosto, bookyear1877
