. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. a very little to the right orleft, to avoid patches of darkness and get the best lantern kaleidoscope entirely depends for success upon ACCESSORY INSTRUMENTS 147 this careful adjustment of the light. The rays, passingthrough the objects, strike rather downwards upon the mirrors,and are again reflected rather upwards ; and in many instru-ments the effect is better if the front lens is somewhat in-clined, so as to be perpendicular to the course of the kaleidoscope should al
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. a very little to the right orleft, to avoid patches of darkness and get the best lantern kaleidoscope entirely depends for success upon ACCESSORY INSTRUMENTS 147 this careful adjustment of the light. The rays, passingthrough the objects, strike rather downwards upon the mirrors,and are again reflected rather upwards ; and in many instru-ments the effect is better if the front lens is somewhat in-clined, so as to be perpendicular to the course of the kaleidoscope should always be warmed before use, toprevent dew upon the mirrors, if the night is at all cold. I have seen a beautiful lantern kaleidoscope, speciallyconstructed by Mr. Darker, in which the mirrors were adjust-able by a screw to any angle through a considerable a form must necessarily be expensive; but an instrumentof this land is far removed from a mere lantern toy, andbecomes at once an exquisite piece of experimental appa-ratus for demonstrating the laws and phenomena of Pig. 77 Aphengescope Fio. 78 80. Opaque Pictures.—Another simple instrument forexhibiting cartes de visite and other opaque objects, such asthe works of a watch, is often called the Aphengescope—themania for giving Greek names to lantern affairs is inexplicableto the ordinary mind. The usual arrangements are shown infigs. 77 and 78, one being adapted for two lanterns, and the l2 148 OPTICAL PROJECTION other for a single one, which latter, however, even with thelime-light, does not afford sufficient illumination to exhibit acarte, de visite more than three or four feet in the double arrangement in fig. 78, the two lanternsL l are turned away from the screen, the objectives removed,and their two nozzles fixed to holes cut to fit them in the boxb. To the back of this box the two grooved doors d d areattached by a common hinge, so that when one door is closedthe other
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
