. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ooking-glass, each about 2 incheslong by | inch wide, mounting them with wax on small wooden feet. Theseare to be arranged ona piece of blackenedboard a, supported by astand, and so arrangedthat the row together,at some little distancefrom the prism p, aboutcovers the whole widthof the spectrum-bandat that spot. Eachmirror is then adjustedto throw its strip of colour on the same spot on the screen taking away one or more mirrors, and so suppressing anyof the colours, again we get colour
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ooking-glass, each about 2 incheslong by | inch wide, mounting them with wax on small wooden feet. Theseare to be arranged ona piece of blackenedboard a, supported by astand, and so arrangedthat the row together,at some little distancefrom the prism p, aboutcovers the whole widthof the spectrum-bandat that spot. Eachmirror is then adjustedto throw its strip of colour on the same spot on the screen taking away one or more mirrors, and so suppressing anyof the colours, again we get colour, whereas all the coloursgave white. A better method of recompounding the colours is to use acylindrical lens, which can easily be so adjusted between theprism and screen as to focus the slit again in an imagewhich appears sharp and white. The cylindrical lens shouldbe rather long in focus, from 10 to 15 inches, to produce agood effect; the usual short-focus cylindrical lenses make theslit appear much too broad. A large cylindrical jar full ofwarm water (else moisture will condense upon it), may be. LIGHT: COLOUR 287
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License: Licensed
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
