. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. ngine, such as may be boughtfor a dollar or two, may have a light paper disk fittedfor it to turn, but if sunlight be used, care must betaken lest it take fire in the focus of the suns rays. An oxyhydrogen lantern may be used for such objective will need to be removed, and the perfo-rated disk placed so that the most of the light goesthrough the holes when they are in position, and theunused light cut off from entering the room by blackcloth or som
. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. ngine, such as may be boughtfor a dollar or two, may have a light paper disk fittedfor it to turn, but if sunlight be used, care must betaken lest it take fire in the focus of the suns rays. An oxyhydrogen lantern may be used for such objective will need to be removed, and the perfo-rated disk placed so that the most of the light goesthrough the holes when they are in position, and theunused light cut off from entering the room by blackcloth or some other provision. Otherwise it will beused just as with sunlight. THE CHROMATROPE. This instrument consists of two disks of glass somounted that they may be rotated in opposite direc-tions. Various designs are painted upon the disks,and fine effects may be obtained by projecting them inthe ordinary way with the lantern or the parte instead of using disks of glass, disks are made ofwire gauze, perforated tin, or paper or lace, very curiousinterference figures are produced, and this form iftcalled the eidotrope. LIGHT. 143. The accompanying figure represents a chromatropewith an arrange-ment for quicklyreplacing onedisk by anotherof different pat-tern. Rotationis given by fric-tion this formthere is a diskwith the so-calledseven primarycolors to illus-trate Newtons theory of colors, i ^ 5 one to illustrate Brewsters theory, two to illustrateYoungs theory, and a chameleon top, designed byPresident Morton, of Stevens Institute, Hoboken. The effects with all the forms of chromatropes aredue to persistence of vision. Interesting subjective effects may be observed byprojecting in the ordinary way bits of colored glass aninch or two square, so as to have upon the screen a largepatch of color with a boundary of white light. The eyesmust be fixed attentively upon the colored patch forabout half a minute, when the colored piece must bequickly removed, the eyes to
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherbosto, bookyear1877
