Scientific amusements . e careful in the blending of thecolours so as to produce the proper result. By adoptingtthis suggestion many amusing experiments may be at-tempted. But in any case, the ring represented can beobtained at most jewellers shops at a small cost, and theexperiment may be tried. Persistence of Impressions on the Retina. the imp on the ceiling. This experiment, which can be performed with the aidof the next illustration, is one appertaining to the principleof persistence of impressions on the retina, to which mustbe added that of complementary colours. PERSISTENCE OF IMPRESSIO
Scientific amusements . e careful in the blending of thecolours so as to produce the proper result. By adoptingtthis suggestion many amusing experiments may be at-tempted. But in any case, the ring represented can beobtained at most jewellers shops at a small cost, and theexperiment may be tried. Persistence of Impressions on the Retina. the imp on the ceiling. This experiment, which can be performed with the aidof the next illustration, is one appertaining to the principleof persistence of impressions on the retina, to which mustbe added that of complementary colours. PERSISTENCE OF IMPRESSIONS ON THE RETINA, 83 Look Steadily wjth both eyes at the white figure in theillustration, on a black ground, particularly keeping yoUrgaze ^xed on the band in the centre ; then, just whenyour eyes are beginning to feel tired-—say in half aminute—look up to the ceiling, and in a few secondsyou will perceive the outline of the imp, in grey, on theceiling, repeatedly. This experiment will gain by being made in a strong. 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 experiments.
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
