lluaion 

 magination 



SCIENTIFIC SIDE-LIGHTS 



320 



entire window, and, after standing still 

 awhile, begins to glide away, we judge that 

 it is our train which is moving, and that the 

 other train is still. If, however, we catch 

 a glimpse of any part of the station through 

 the windows, or between the cars of the 

 other train, the illusion of our own move- 

 ment instantly disappears, and we perceive 

 the other train to be the one in motion. 

 This, again, is but making the usual and 

 probable inference from our sensation. 

 JAMES Psychology, vol. ii, ch. 19, p. 90. 

 (H. H. & Co., 1899.) 



1560. ILLUSION OF PERCEPTION 



A Mother's Needless Terror The Seeing of 

 Complementary Colors. The eye also under 

 some circumstances may lose its sensibility 

 for particular colors, or be thrown into such 

 an unusual state as to present all objects to 

 the mind under the appearance of a false 

 color. Thus, if a person looks fixedly for a 

 time at a bright red object and then turns 

 his eye to a white wall, he will perceive a 

 green image of the red object depicted on 

 the white surface. A lady of our acquaint- 

 ance was once thrown into an alarming but 

 laughable paroxysm of terror by an effect of 

 this kind. She had been for some hours at- 

 tentively sewing on a bright crimson dress, 

 when her attention was directed towards her 

 child, who in its sport had thrown itself on 

 the carpet; its face appeared of the most 

 ghastly hue, and the affrighted mother 

 screamed in agony that her child was in con- 

 vulsions; the other inmates of the house 

 hastened to her assistance, but they were 

 surprised to find the little one smiling in 

 perfect health. The sanity of the mother 

 became the natural object of solicitude until 

 the effect was properly referred to the im- 

 pression made on her eye by the crimson 

 cloth. HENRY Color-Blindness, Scientific 

 Writings, vol. i, p. 234. (Sm. Inst., 1886.) 



1561. ILLUSION THE LOT OF ALL 



MEN Absolute Truth Sought in Fain. Not- 

 withstanding the flattering supposition of 

 common sense, that illusion is essentially an 

 incident in abnormal life, the careful ob- 

 server knows well enough that the case is 

 far otherwise. There is, indeed, a view of 

 our race diametrically opposed to the flat- 

 tering opinion referred to above, namely, the 

 humiliating judgment that all men habitu- 

 ally err, or that illusion is to be regarded as 

 the natural condition of mortals. This idea 

 has found expression not only in the cynical 

 exclamation of the misanthropist that most 

 men are fools, but also in the cry of despair 

 that sometimes breaks from the weary 

 searcher after absolute truth, and from the 

 poet when impressed with the unreality of 

 his early ideals. SULLY Illusions, ch. 1, p. 

 2. (A., 1897.) 



1562. ILLUSION THROUGH MENTAL 

 SUGGESTION The following, related by Dr. 

 Tuke, shows in an admirable manner how 

 similar impressions may be revived, and fal- 

 sify the perceptions of a number of persons : 



" During the conflagration at the Crystal 

 Palace, in the winter of 1866-67, when the 

 animals were destroyed by the fire, it was 

 supposed that the chimpanzee had succeeded 

 in escaping from its cage. Attracted to the 

 roof with the expectation in full force, men 

 saw the unhappy animal holding on to it 

 and writhing in asrony to get astride one of 

 the iron ribs. It need not be said that its 

 struggles were watched by those below with 

 breathless suspense, and, as the newspapers 

 informed us, * with sickening dread.' But 

 there was no animal whatever there; and 

 all this feeling was thrown away upon a 

 tattered piece of blind, so torn as to re- 

 semble to the eye of fancy the body, arms, 

 and legs of an ape!" ELDRIDGE -GREEN 

 Memorv and Its Cultivation, pt. i, ch. 7, p. 

 172. (A., 1900.) 



1563. ILLUSION THROUGH PRECON- 

 CEPTION Seeing the Expected. We [some- 

 times] perceive a wrong object because our 

 mind is full of the thought of it at the 

 time, and any sensation which is in the 

 least degree connected with it touches off, 

 as it were, a train already laid, and gives 

 us a sense that the object is really before 

 us. Here is a familiar example : 



"If a sportsman, while shooting wood- 

 cock in cover, sees a bird about the size and 

 color of a woodcock get up and fly through 

 the foliage, not having time to see more 

 than that it is a bird of such a size and 

 color, he immediately supplies by inference 

 the other qualities of a woodcock, and is 

 afterwards disgusted to find that he has 

 shot a thrush. I have done so myself, and 

 could hardly believe that the thrush was the 

 bird I had fired at, so complete was my men- 

 tal supplement to my visual perception." 



As with game, so with enemies, ghosts, 

 and the like. Any one waiting in a dark 

 place and expecting or fearing strongly a 

 certain object, will interpret any abrupt sen- 

 sation to mean that object's presence. The 

 boy playing " I spy," the criminal skulking 

 from his pursuers, the superstitious person 

 hurrying through the woods or past the 

 churchyard at midnight, the man lost in the 

 woods, the girl who tremulously has made 

 an evening appointment with her swain, all 

 are subject to illusions of sight and sound 

 which make their hearts beat till they are 

 dispelled. JAMES Psychology, vol. ii, ch. 19, 

 p. 95. (H. H. & Co., 1899.) 



1564. ILLUSIONS IN NATURE The 



Specter of the Brocken. There is a wonder- 

 ful exhibition of shadow to be seen under 

 certain conditions of the atmosphere on one 

 of the peaks of the Hartz Mountains, called 

 the Brocken. If one or more people stand 

 on the summit at sunrise they can see an 

 enlarged shadow of themselves as well as 

 the top of the mountain, together with a 

 house with a tower on it, standing out 

 against the sky in enormous proportions; 

 the clouds and mist form a screen to catch 

 the shadows, and, while it is as easily ex- 



