561 



SCIENTIFIC SIDE-LIGHTS 



Progress 

 Protection 



possible reason can there be for excluding 

 such indications of the past and the future 

 from a revelation made by him who knows 

 perfectly the end from the beginning, and 

 to whom the future results of human ac- 

 tions to the end of time must be as evident 

 as the simplest train of causes and effects 

 is to us? [See PREDICTION.] DAWSON Facts 

 and Fancies in Modern Science, lect. 6, p. 

 231. (A. B. P. S.) 



2766. PROPORTION BETWEEN EX- 

 TENT OF AURORA AND ITS HEIGHT 



It must be noted that the extent of the 

 aurora appears to bear a certain relation 

 to its height. The extensive auroras those, 

 for instance, which are seen simultaneously 

 in the two hemispheres appear to shine 

 from an immense height. On the other 

 hand, the auroras which are at low levels 

 are always very limited in area, or even 

 purely local. This appears to be another 

 point in favor of the opinion already stated, 

 namely, that these two categories of auroras 

 are really distinct phenomena, both in their 

 properties and in their origin. ANGOT Au- 

 rora Borealis, ch. 4, p. 56. (A., 1897.) 



2767. PROSPERITY MADE POSSIBLE 

 BY SOCIAL ORDER Utility of Ancient Creeds 

 and Cults. Even the creeds and cults of 

 mankind, whatever view you may take of 

 the divine element underneath them, have 

 been thought out and wrought out with 

 infinite pains from time to time by earnest 

 souls. But they had their origin in the 

 cradle-land and in the infancy of our race. 

 What we enjoy is only the full-blown flower, 

 the perfected fruit of which they possessed 

 the germ. Let me enforce this idea, as we 

 glorify the material prosperity of the nine- 

 teenth century, that many centuries ago men 

 sat down and with great pains and sorrow 

 invented the language, the art, the indus- 

 tries, the social order which made our ma- 

 chines feasible and desirable. MASON The 

 Birth of Invention (Address at Centenary of 

 American Patent System, Washington, D. C., 

 1891; Proceedings of the Congress, p. 407). 



2768. PROSPERITY OF NATIONS 

 THE RESULT OF SCIENTIFIC PROGRESS 



An equal appreciation of all branches of 

 the mathematical, physical, and natural sci- 

 ences is a special requirement of the present 

 age, in which the material wealth and the 

 growing prosperity of nations are principal- 

 ly based upon a more enlightened employment 

 of the products and forces of Nature. The 

 most superficial glance at the present con- 

 dition of Europe shows that a diminution 

 or even a total annihilation of national pros- 

 perity must be the award of those states 

 who shrink with slothful indifference from 

 the great struggle of rival nations in the 

 career of the industrial arts. It is with na- 

 tions as with Nature, which, according to 

 a happy expression of Goethe, " knows no 

 pause in progress and development, and at- 

 taches her curse on all inaction." The 



propagation of an earnest and sound knowl- 

 edge of science can therefore alone avert th& 

 dangers of which I have spoken. Man can- 

 not act upon Nature, or appropriate her 

 forces to his own use, without comprehend- 

 ing their full extent and having an inti- 

 mate acquaintance with the laws of the 

 physical world. HUMBOLDT Cosmos, vol. i,. 

 int., p. 53. (H., 1897.) 



2769. PROTECTION BY DESTRUC- 

 TION OF ENEMIES The Sparrow-hawk De- 

 vours Destroyers of Crops. The sparrow- 

 hawk has a perfectly clean record, as far as, 

 chickens go, not one of the 320 whose stom- 

 achs were examined by Dr. Fisher having, 

 partaken of poultry, while no less than 

 215 had eaten insects and 89 had captured 

 mice. Grasshoppers are the sparrow-hawk's 

 chief food, and we may often see him hover- 

 ing over the fields with rapidly moving 

 wings. Then, dropping lightly down on some 

 unsuspecting victim below, he returns to 

 the bare limb or stub he uses for a lookout 

 station, uttering an exultant killy killy 

 killy as he flies. CHAPMAN Bird-Life, ch. 

 7, p. 120. (A., 1900.) 



2770. PROTECTION BY DISTASTE- 

 FULNESS Even Parasites Avoid the Mon- 

 arch Butterfly. Mr. Samuel H. Scudder,, 

 who has largely bred North- American but- 

 terflies, has found so many of the eggs and 

 larvae destroyed by hymenopterous and dip- 

 terous parasites that he thinks at least nine- 

 tenths, perhaps a greater proportion, never 

 reach maturity. Yet he has never found any 

 evidence that such parasites attack either the: 

 egg or the larva of the inedible Danais ar- 

 chippus, so that in this case the insect is. 

 distasteful to its most dangerous foes in 

 all the stages of its existence, a fact which 

 serves to explain its great abundance and 

 its extension over almost the whole world. 

 WALLACE Darwinism, ch. 9, p. 161. (Hum.,, 

 1897.) 



2771. PROTECTION BY MIMICRY 

 Spiders Resembling Leaves Both in Action 

 and Appearance. Green-leafed bushes are 

 frequented by vividly green epeiras [spi- 

 ders], but the imitative resemblance does 

 not quite end here. The green spider's 

 method of escape, when the bush is roughly 

 shaken, is to drop itself down on the earth, 

 where it lies simulating death. In falling, 

 it drops just as a green leaf would drop, 

 that is, not quite so rapidly as a round, 

 solid body like a beetle or a spider. Now 

 in the bushes there is another epeira, in 

 size and form like the last, but differing 

 in color; for instead of a vivid green it is 

 of a faded yellowish white the exact hue of 

 a dead, dried-up leaf. This spider, when it 

 lets itself drop for it has the same pro- 

 tective habit as the other falls not so 

 rapidly as a green freshly broken-off leaf, 

 or as the green spider would fall, but with 

 a slower motion, precisely like a leaf with- 

 ered up till it has become almost light as a 



