Cheapening 



SCIENTIFIC SIDE-LIGHTS 



96 



Others, again, have changed in tint. . . . 

 There are some, also, which have suddenly 

 appeared, have shone with a dazzling bright- 

 ness for several weeks or months, and have 

 then relapsed into obscurity. In a large 

 number a periodical variation of light has 

 been established, in virtue of which certain 

 stars, at first invisible to the naked eye, ap- 

 pear, increase progressively in brightness, 

 then gradually diminish, and disappear, to 

 again reappear after a certain number of 

 days has elapsed; their periodicity is some- 

 times so exact that they are now calculated 

 in advance. FLAMMARION Popular Astron- 

 omy, bk. vi, ch. 3, p. 580. (A.) 



475. CHANGES IN SHAPE OF THE 

 EARTH Alps Thrust Up from beneath the 

 Sea Folded and Contorted Strata. That 

 [the Alps] were in whole or in part once be- 

 neath the sea will not be disputed ; for they 

 are in grfeat part composed of sedimentary 

 rocks which required a sea to form them. 

 Their present elevation above the sea is due 

 to one of those local changes in the shape of 

 the earth which have been of frequent oc- 

 currence throughout geologic time, and 

 which in some cases have depressed the land, 

 and in others caused the sea-bottom to pro- 

 trude beyond its surface. Considering the 

 inelastic character of its materials, the pro- 

 tuberance of the Alps could hardly have 

 been pushed out without dislocation and 

 fracture; and this conclusion gains in prob- 

 ability when we consider the foldings, con- 

 tortions, and even reversals in position of 

 the strata in many parts of the Alps. Such 

 changes in the position of beds which were 

 once horizontal could not have been effected 

 without dislocation. TYNDALL Hours of Ex- 

 ercise in the Alps, ch. 20, p. 230. (A., 

 1898.) 



476. CHANGES IN STRUCTURE OF 

 THE EARTH Rapid Growth of Coral It 

 may be concluded, first, that considerable 

 thicknesses of rock have certainly been 

 formed within the present geological era by 

 the growth of corals and the accumulation 

 of their detritus ; and, secondly, that the in- 

 crease of individual corals and of reefs, both 

 outwards or horizontally, and upwards or 

 vertically, under conditions favorable to 

 such increase, is not slow, when referred 

 either to the standard of the average oscilla- 

 tions of level in the earth's crust, or to the 

 more precise but less important one of a 

 cycle of years. DARWIN Coral Reefs, ch. 4, 

 p. 107. (A., 1900.) 



477. CHANGES IN THE BRAIN Pres- 

 ent State a Combined Result of Circum- 

 stance and Sensibility. Whilst we think, 

 our brain changes, and, like the aurora bore- 

 alis, its whole internal equilibrium shifts 

 with every pulse of change. The precise na- 

 ture of the shifting at a given moment is a 

 product of many factors. The accidental 

 state of local nutrition or blood-supply may 

 be among them. But just as one of them 

 certainly is the influence of outward objects 



on the sense-organs during the moment, so 

 is another certainly the very special sus- 

 ceptibility in which the organ has been left 

 at that moment by all it has gone through 

 in the past. Every brain-state is partly de- 

 termined by the nature of this entire past 

 succession. Alter the latter in any part, and 

 the brain-state must be somewhat different. 

 Each present brain-state is a record in 

 which the eye of Omniscience might read all 

 the foregone history of its owner. JAMES 

 Psychology, vol. i, ch. 9, p. 234. (H. H. & 

 Co., 1899.) 



478. CHANGES, MOLECULAR, IN 

 PLANTS DUE TO LIGHT Colors of Flower 

 Petals Chlorophyl Produced by Sun. 

 Light is an all-important agent of molecu- 

 lar changes in organic substances. . . . 

 The characteristic matter called chlorophyl, 

 which gives the green color to leaves, makes 

 its appearance whenever the blanched shoots 

 of plants are exposed to the sun; the petals 

 of flowers, uncolored while in the bud, ac- 

 quire their bright tints as they unfold ; and 

 on the outer surfaces of animals analogous 

 changes are induced. SPENCER Biology, pt. 

 i, ch. 2, p. 35. (A., 1900.) 



479. CHANGES OF A STAR Once 

 Bright as Sirius, Now Almost Invisible. 

 Changes such as these [the repeated increase 

 and decline of light of a star in the ship 

 Argo] or even one of these changes if oc- 

 curring in the case of our own sun, would 

 destroy life very quickly from the face of 

 the earth, and probably from all the in- 

 habited planets of the solar system. The 

 mere change from the second magnitude to 

 a brightness approaching that of Sirius im- 

 plies an increase of emission of light and 

 heat more than tenfold. But from this 

 amazing access of splendor how . wonderful 

 has been the falling off by which the star 

 has been rendered almost invisible. It is 

 absolutely certain that this star, once doubt- 

 less a sun, and probably, like our own sun, 

 the center of a scheme of circling worlds, 

 gives out, day by day, far less than the hun- 

 dredth part of the light and heat which it 

 gave out daily only thirty years ago. PROC- 

 TOR Expanse of Heaven, p. 197. (L. Gr. & 

 Co., 1897.) 



480. CHANGES, SUBTERRANEAN 



Defy Human Perception Imagination Often 

 at Fault Prejudices Arising from Our Not 

 Seeing Subterranean Changes. Nor is his 

 [man's] position less unfavorable when, be- 

 holding a volcanic eruption, he tries to con- 

 ceive what changes the column of lava has 

 produced, in its passage upwards, on the in- 

 tersected strata; or what form the melted 

 matter may assume at great depths on cool- 

 ing; or what may be the extent of the sub- 

 terranean rivers and reservoirs of liquid 

 matter far beneath the surface. It should 

 therefore be remembered that the task im- 

 posed on those who study the earth's history 

 requires no ordinary share of discretion ; for 



