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SCIENTIFIC SIDE-LIGHTS 



it shows the moon as if viewed with the 

 naked eye at a distance of forty miles. But 

 this seeming advantage is neutralized by the 

 weakening of the available light through ex- 

 cessive diffusion, as well as by the troubles 

 of the surging sea of air through which the 

 observation must necessarily be made. Pro- 

 fessor Newcomb, in fact, doubts whether 

 with any telescope our satellite has ever 

 been seen to such advantage as it would 

 be if brought within 500 miles of the un- 

 armed eye. CLERKE History of Astronomy, 

 pt. i, ch. 6, p. 148. (Bl., 1893.) 



1591. IMPERFECTION OF THE GEO- 

 LOGICAL RECORD Destructive Agencies 

 Obliterate the Remains. It can be demon- 

 strated that the geological record must be 

 incomplete, that it can only preserve re- 

 mains found in certain favorable localities 

 and under particular conditions; that it 

 must be destroyed by processes of denuda- 

 tion, and obliterated by processes of meta- 

 morphosis. Beds of rock of any thickness, 

 crammed full of organic remains, may yet, 

 either by the percolation of water through 

 them or by the influence of subterranean 

 heat, lose all trace of these remains, and 

 present the appearance of beds of rock 

 formed under conditions in which living 

 forms were absent. Such metamorphic rocks 

 occur in formations of all ages; and in 

 various cases there are very good grounds 

 for the belief that they have contained or- 

 ganic remains, and that those remains have 

 been absolutely obliterated. HUXLEY Ameri- 

 can Addresses, lect. 2, p. 42. (A., 1898.) 



1592. IMPERFECTIONS OF THE 



EYE Yet a Marvel to the Reflecting Mind. 

 And here, in passing, I am reminded of the 

 common delusion that the works of Nature, 

 the human eye included, are theoretically 

 perfect. The eye has grown for ages to- 

 wards perfection; but ages of perfecting 

 may be still before it. ... A long list of 

 indictments might indeed be brought against 

 the eye its opacity, its want of symmetry, 

 its lack of achromatism, its absolute blind- 

 ness, in part. All these taken together 

 caused Helmholtz to say that if any opti- 

 cian sent him an instrument so full of de- 

 fects he would be justified in sending it back 

 with the severest censure. But the eye is 

 not to be judged from the standpoint of 

 theory. It is not perfect, as I have said, 

 but on its way to perfection. As a prac- 

 tical instrument, and taking the adjust- 

 ments by which its defects are neutralized 

 into account, it must ever remain a marvel 

 to the reflecting mind. TYNDALL Lectures 

 on Light, lect. 1, p. 8. (A., 1898.) 



1593. IMPERIpUSNESS OF WRONG 

 HABIT Student Revisiting Paris Unconscious- 

 ly Seeks Old Room. Not only is it the 

 right thing at the right time that we thus 

 involuntarily do [when a habit has become 

 fixed], but the wrong thing also, if it be 

 an habitual thing. Who is there that has 

 never wound up his watch on taking off his 



waistcoat in the daytime, or taken his 

 latch-key out on arriving at the door-step 

 of a friend? Very absent-minded persons 

 in going to their bedroom to dress for din- 

 ner have been known to take off one gar- 

 ment after another and finally to get into 

 bed, merely because that was the habitual 

 issue of the first few movements when per- 

 formed at a later hour. The writer well re- 

 members how, on revisiting Paris after ten 

 years' absence, and finding himself in the 

 street in which for one winter he had at- 

 tended school, he lost himself in a brown 

 study, from which he was awakened by find- 

 ing himself upon the stairs which led to 

 the apartment in a house many streets 

 away in which he had lived during that 

 earlier time, and to which his steps from 

 the school had then habitually led. JAMES 

 Psychology, vol. i, ch. 4, p. 114. (H. H. & 

 Co., 1899.) 



1594. IMPERSONATION The Dra- 

 matic Impulse Strong in Children. The 

 dramatic impulse, the tendency to pretend 

 one is some one else, contains this pleasure 

 of mimicry as one of its elements. Another 

 element seems to be a peculiar sense of 

 power in stretching one's own personality so 

 as to include that of a strange person. In 

 young children this instinct often knows no 

 bounds. For a few months in one of my 

 children's third year, he literally hardly 

 ever appeared in his own person. It was 

 always, " Play I am So-and-so, and you are 

 So-and-so, and the chair is such a thing, 

 and then we'll do this or that." If you 

 called him by his name, H., you invari- 

 ably got the reply, " I'm not H:, I'm a 

 hyena, or a horse-car/' or whatever the 

 feigned object might be. He outwore this 

 impulse after a time; but while it lasted 

 it had every appearance of being the auto- 

 matic result of ideas, often suggested by 

 perceptions, working out irresistible motor 

 effects. JAMES Psychology, vol. ii, ch. 24, p. 

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



1595. IMPERSONATION CREATING 



MYTHS Origin of the Three Fates Past, 

 Present, Future. Another well-known 

 mythic group shows again how what to us 

 moderns are but ideas expressed in words, 

 took personal form in the minds of the an- 

 cients. In the classic books of Greece and 

 Eome we read of the three fate-spinners, the 

 Moirai or Parcse, and their Scandinavian 

 counterparts appear in the Edda as the 

 three wise women whose dwelling is near the 

 spring under the world-ash Ygdrasill, the 

 Norns who fix the lives of men. The ex- 

 planation of these three mythic beings is 

 that they are in personal shape the Past, 

 Present, and Future, as is shown by the 

 names they bear Was, Is, Shall (Urdhr, 

 Verdhandi, Skuld). TYLOR Anthropology, 

 ch. 15, p. 396. (A., 1899.) 



1596. IMPLEMENTS, NATURAL, 

 EFFECTIVENESS OfBill of Macaw Sur- 

 passes Hammer Hardest Nuts Crushed to 



