We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
DIA GRAM ILL USIONS. 19 The most effective early device for this purpose was the Ross Wheel of Life (Figs. 13 and 14), designed for use in the Optical Lantern, and patented in 1871. The disc bearing the figures is caused to revolve slowly; the opaque disc has one sector removed and travels at such a speed as to make one revolution while the transparent disc moves one stage. Thus in Fig. 13 two figures are seen through the opening in the opaque disc. Its revolution promptly cuts them out of sight, and by the time the opening comes back to the same place the next pair of figures (in slightly different attitudes) are found to occupy the same vertical line. This arrangement is practically a substitution of a one-slot disc for a four-slot one as used by Plateau in the instrument last described. The result of this arrangement is that the lantern screen is full of figures all in motion and in various phases of the same action; but this multiplicity of images is confusing, and attempts were made to show only one figure on the screen at a time. Mr. Beale, of Greenwich, devised a method whereby a face could be shown m motion by means of a series of sixteen pictures illuminated by intermittent flashes. A painting of a human bust was made on a screen, the face being replaced by a hole, behind which could be brought sixteen views of a face in the various stages of a grimace or smile by means of the revolution of a disc on the circumference of which they were painted. A sixteen-holed shutter worked by gearing admitted a flash of light to illuminate the painting for a moment as each face arrived in its proper position, the light being cut off during a quick change to the next ^expression. By means of an ingenious contrivance which allowed only every alternate opening in the shutter to act, and was adjustable to show first one series of eight and then another, the resultant grimace -was varied in a most amusing way. This arrangement,