. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ain preponderatingkinds of work, certain forms of lantern are best adapted; andfor constant work, especially in educational institutions, theform of lantern should therefore be determined with referenceto the kind of work to be chiefly done. The modification and use of the lantern in a cheap and simpleway to project pieces of apparatus as well as slides, was firstsystematised in the schools of Germany. Fig. 81 representssuch a German school lantern. The essential points are that the flange-n
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ain preponderatingkinds of work, certain forms of lantern are best adapted; andfor constant work, especially in educational institutions, theform of lantern should therefore be determined with referenceto the kind of work to be chiefly done. The modification and use of the lantern in a cheap and simpleway to project pieces of apparatus as well as slides, was firstsystematised in the schools of Germany. Fig. 81 representssuch a German school lantern. The essential points are that the flange-nozzle is entirelyremoved, only an open spring-holder stage being left in thefront of the condensers ; that the objective is mounted in aseparate support, which can slide along the double-rail stand 154 OPTICAL PROJECTION and that a small table, adjustable for height, canalso be fixed anywhere on the same base. On this table anypiece of sufficiently small apparatus can be adjusted, andprojected as if it were a slide. The objective is surroundedby a shade to keep stray light from the screen. Ordinary. Fig. 81.—German Lantern slides or diagrams are placed in the spring holder, and pro-jected as usual. This arrangement has been a great deal popularised inEngland by Mr. W. Lant Carpenter in connection with theGilchrist Lecturing Trust; and where actual physical apparatus,and diagrams, are the principal subjects of projection, it canhardly be improved upon for handiness, cheapness, and sim-plicity ; but it is not so well adapted for optical and acousticalexperiments, on account of the stray light. Fig. 82 is anAmerican modification of it, arranged with a special view to APPARA TUS FOR SCIENTIFIC DEMONSTRA TION 155 portability. The rails and legs are here dispensed with ; thelantern body is a mere frame hinged together, with a metaltop, and covered round when in use with thick black cloth; andthe whole is placed on a table. The jet is also modified forcompactness, the usual long met
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
