. The microscope and its revelations. elt by workers whohave not before usedit. The cell contain-ing the solution andworked glass mayeither have its upperend sealed hermeti-cally with paraffin, orbe simply carefullycorked; the latterplan, if the cork iscarefully made, ad-mits of the easyopening of the celland renewal of thefluid. A diagram-matic illustration ofthe effect of the useof the screen is givenin fig. 267, whichrepresents the bandof colour passedthrough the F-linescreen. The greenis represented by thehorizontal lines, andthe blue, in whichthe F line is situated,by the diagonal
. The microscope and its revelations. elt by workers whohave not before usedit. The cell contain-ing the solution andworked glass mayeither have its upperend sealed hermeti-cally with paraffin, orbe simply carefullycorked; the latterplan, if the cork iscarefully made, ad-mits of the easyopening of the celland renewal of thefluid. A diagram-matic illustration ofthe effect of the useof the screen is givenin fig. 267, whichrepresents the bandof colour passedthrough the F-linescreen. The greenis represented by thehorizontal lines, andthe blue, in whichthe F line is situated,by the diagonal cell itself isprepared by the Ley-bold s process, and isfused at the jointsand never leaks; astill simpler and lessexpensive means ofmaking >uch a filterlias been devised byDr. A. Meithe, pro-fessor of spectralanalysis at consists ofa 1 rough containingn inch in thickness of saturated solution of acetate of copperfiltered; a variation in the thickness of the troughs or tanksrable, but the results are MICEO-SPECTEOSCOPE 323 Equally perfect monochromatic illumination can be obtained byprismatic dispersion. A method of approximating to monochromatic illumination hasbeen devised by Mr. Nelson which answers admirably with anordinary ^-inch wick paraffin lamp. Briefly, the rays proceedingfrom the radiant are passed through a slit, as in fig. 2QS, anddispersed by a prism of glass, and by means of a second slit anyportion we wish may be selected from the spectrum to be used forthe purpose required. First an image of the edge of the flame is focussed upon the slitby means of a bulls-eye consisting of three lenses; next the slit is placed in the principal focus of a lens known as a Wray 5 x 4 R R, f working at ~- (this lens is not shown in the cut). In the parallelD*O beam from this lens and close to it is placed an equilateral prism of dense flint set at minimum deviation. Close to the prism is placed f another Wray 5 x 4 R R. working at ~~. If a cardb
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
