. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. f an inch between this nozzle and the hole in the box. Had Ifound his arrangement described earlier, I should probably have adopted bothit, and the ingenious inventors conclusion that it was indispensable ; as it isI prefer (perhaps naturally) the smaller boxes as more easily adjusted, and theclosed supply as more certain and using less wind. 264 OPTICAL PROJECTION to the plane-mirror m, which can be revolved on the perpen-dicular pivot p. Thence it is reflected in the direction of thescreen
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. f an inch between this nozzle and the hole in the box. Had Ifound his arrangement described earlier, I should probably have adopted bothit, and the ingenious inventors conclusion that it was indispensable ; as it isI prefer (perhaps naturally) the smaller boxes as more easily adjusted, and theclosed supply as more certain and using less wind. 264 OPTICAL PROJECTION to the plane-mirror m, which can be revolved on the perpen-dicular pivot p. Thence it is reflected in the direction of thescreen at s, and it will be manifest that a slight revolution ofm opens out the scroll. This arrangement also enables us to combine any two setsof vibrations in harmonic addition, as well as an octave gives the well-known 8-figure ; but ifboth reed-boxes are fixed perpendicularly and a scroll openedout by rotating tbe mirror m, the harmonic combination is ex-ceedingly instructive, as is also the optical representation ofany slight departure from unison, or any other Tig. 110.—Plan of Apparatus Such an apparatus is far the best for the projection ofcompound figures, being superior to the most expensive forksin many respects. For its efficiency, it is also far the possesses the following advantages, which are not found incombination in any other apparatus so far as I know. (a) It projects with ease all compound figures and project beats, all that is necessary is to fix the reed-boxee (fig. 140), perpendicularly, the same as the other, inserta second reed in unison with r, and having tuned (see g below)rotate the mirror m, to give the scroll. When scrolls are notwanted the mirror m is simply left unmoved. SOUND 265 (b) All the notes are audible; more so than with forks. (c) Any note within the speaking range of the boxes canbe added at any time for a few shillings. (d) Any interval can be changed for any other (so far asno
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
