. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ich was originally devised by Mr. The long steel spindle has a longitudinal groovecut, which slides up or down over a feather in the cog-wheel;and there is also a long-pitched spiral groove which givesthe required motion. To this Mr. Newton has added asmall wheel on the manual rod, in which notches are cut atproper intervals. A spring detent bears against these notches,so that the exact spot at which the line should be held is THE UMELTGHT 65 felt by an almost imperceptible click. T
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. ich was originally devised by Mr. The long steel spindle has a longitudinal groovecut, which slides up or down over a feather in the cog-wheel;and there is also a long-pitched spiral groove which givesthe required motion. To this Mr. Newton has added asmall wheel on the manual rod, in which notches are cut atproper intervals. A spring detent bears against these notches,so that the exact spot at which the line should be held is THE UMELTGHT 65 felt by an almost imperceptible click. The whole lime is thustraversed in one continuous spiral from top to bottom, eachhalting-spot on the surface being exactly marked out. Thewhole jet is shown in proportion, with the further addition ofa cut-off arrangement devised by Mr. A. Pringle, in fig. 65,p. 118. Mr. E. G. Wood has also constructed a jet with a click orcheck mechanism, so arranged, that when a second revolutionof the lime takes place, the places where the jet impinges arehalf-way between those of the previous revolution. In this. Fig. 43.—Lime-turning arrangement way less perpendicular motion of the lime becomes is another screw motion, with a separate handle, foradjusting the distance of the lime from the jet. The jetitself is packed with gauze, and the tube and nipple are bentlike an elbow, which Mr. Wood considers to produce a bettermixture of the gases. As will be seen, my experiments—andthey have been long and many—have led me to a differentconclusion on this point, and moreover such nipples cannotconveniently be employed of different sizes, which is verydesirable. The lime-turning movement is, however, ingeniousand good, and this jet would doubtless be more widely used 66 OPTICAL PROJECTION were it not for its cost, which is more than double that of thepreceding. Mr. Wood has further applied to his jet a shield or jacketof copper surrounding the lime at a little distance, except a
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
