The Science record; a compendium of scientific progress and discovery . ank paper on theright. The artist now stands as represented in our illus- MISCELLANEOUS. 571 tration—that is, so as to look down upon the surface of theglass at a very oblique angle. The original .drawing isreflected from the polished surface of the pane to his eye,and at the same time he sees the white paper through thetransparent glass, so that the lines of the model appeartransferred, but reversed of course, upon the paper. Theseneed only be followed with the pencil, and the outline ismade. The apparatus is not of great
The Science record; a compendium of scientific progress and discovery . ank paper on theright. The artist now stands as represented in our illus- MISCELLANEOUS. 571 tration—that is, so as to look down upon the surface of theglass at a very oblique angle. The original .drawing isreflected from the polished surface of the pane to his eye,and at the same time he sees the white paper through thetransparent glass, so that the lines of the model appeartransferred, but reversed of course, upon the paper. Theseneed only be followed with the pencil, and the outline ismade. The apparatus is not of great use where reliablework is required, ard indeed seems to us little more thana means of amusement. There are two reflections of theoriginal thrown upon the eye, due to the rays strikingboth surfaces of the glass at unequal angles, which tendto confuse and render the outline indistinct. Again, un-less the original be brilliantly illuminated, the shadow isso faint that the black lines of the pencil appear to blotout the finer details of the lighter portions. The glass. AIDS TO DRAWING.—FIG. 5.—THE REFLECTING DRAWING-BOARD. must be besides accurately perpendicular, as otherwise avery distorted image is produced, and also be entirely freefrom defects due to imperfect annealing. The best kind touse, we think, is thin French plate, polished as highly aspossible. 572 SCIENCE RECORD. THE CAMERA LUCIDA. Probably the most really reliable optical device is the camera luczda, represented in Figs. 6 and 7,a simple arrangement extensively used by professional ar- <. ^J ^^^ tists for saving time in sketchingaccurate outlines,of either the samedimensions asthose of the origi-nals, or enlargedor reduced. Theprinciple of itsconstruction willbe readily under-stood from thesmall sketchmarked 2 in Fig. glass is sim-ply a four-sidedprism, having oneright angle, oneof 1350, and twoof 672^°. Whenrays from the object pass
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Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjecttechnology
