. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. lide, a smaller surface ismuch more brightly illu-minated. The stage, in thisform of attachment, is en-tirely open, and consists ofa rotating diaphragm-platepierced with apertures ofappropriate sizes for thevarious objects, which areheld by simple clips. Theobjective fitting is screwed for ordinary microscopic objectives, any of which may be tried,and used if found sufficiently fiat in field. If none such can befound amongst the owners own objectives, the most suitablepowers are the 2^ inch,
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. lide, a smaller surface ismuch more brightly illu-minated. The stage, in thisform of attachment, is en-tirely open, and consists ofa rotating diaphragm-platepierced with apertures ofappropriate sizes for thevarious objects, which areheld by simple clips. Theobjective fitting is screwed for ordinary microscopic objectives, any of which may be tried,and used if found sufficiently fiat in field. If none such can befound amongst the owners own objectives, the most suitablepowers are the 2^ inch, 1| inch, and -£$ inch from the list ofthe larger instrument described in Chapter XIII. Fair resultscan be obtained with powers as high as T40 inch. Since its first production, this attachment has found suchgeneral acceptance, thai some form closely resembling it cannow be obtained of almost any respectable optician, with orwithout certain modifications presumed to be most of these the reader may be left to judge for himself;but he should be distinctly cautioned against one, viz. a. Fig. 80 152 OPTICAL PROJECTION mechanical stage. The average Shopticisna.—a very differentbeing from the more serious optician—is very fond of aninstrument with as many screws, and racks, and adjust-ments as he can possibly crowd upon it. Many a purchaseris fond of the same ; and by all means let the one sell as muchas he can, and the other buy as much bright brass as he the serious worker is of another sort; and him I wouldwarn that all useless lumber of the kind is, to an ordinaryoperator in the dark, simply a source of embarrassment anddistress. I have worked too long at this subject not to befamiliar with all manner of stages ; and affirm without hesita-tion, that a mechanical stage is not only useless, but a positivehindrance, for all but a limited class of work which will bementioned in due course. An attachment of this kind will do a great deal of reallyinterest
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
