Scientific amusements . Fig. 70.—Figure for Experiment of Persistence of Impressions on the Retina. light. I If the imp be red m the silhmette the impressionwill come out in green, which is the complementarycolour of red. It is rather comical when a nuniber ofpeople try the experiment simultaneously, all with headsin the air waiting for the irtip to appear. A card, suchas the ace of hearts, may replace the design, and insteadof the ceiling, a sheet of white paper may be looked at 84 LIGHT. after the figure has been studied. This experiment canbe varied to any extent—a white, black, or green im
Scientific amusements . Fig. 70.—Figure for Experiment of Persistence of Impressions on the Retina. light. I If the imp be red m the silhmette the impressionwill come out in green, which is the complementarycolour of red. It is rather comical when a nuniber ofpeople try the experiment simultaneously, all with headsin the air waiting for the irtip to appear. A card, suchas the ace of hearts, may replace the design, and insteadof the ceiling, a sheet of white paper may be looked at 84 LIGHT. after the figure has been studied. This experiment canbe varied to any extent—a white, black, or green imagewill be reproduced in the complementary blue, white, orred. If painted green on a red ground the result willappear as red on green. The annexed illustration colouredwill suffice for any Fig. 7i.—The Mule Rigolo. THE MULE RIGOLO. We have seen on the boulevards a very simple zoo-troptic apparatus represented in the cut above (Fig. 71).It is composed of four panels of cardboard, mounted ata right angle around a hollow axis. This cardboard PERSISTENCE OF IMPRESSIONS ON THE RETINA. 85 arrangement can be put on a vertical stem, fixed on apedestal, on which it turns >vith ease. Each panel con-tains a zpotroptic design, and the impression of eachfigure on the retina gives the spectator the idea of asingle figure with different action ; at the different periodsof a movement comprised between its extreme limits. Fig. 72.—The Silhouette Portraits. THE SILHOUETTE PORTRAITS. Take a large sheet of paper, black on one side andwhite on the other. Fix it by means of pins to the wallso that the white surface is outermost. On a table closeby place a good lamp, and let the person whose portrait 7 86 LIGHT. you wish to take stand between the lamp and the sheetof white paper. You c
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
