Valise 

 Javes 



SCIENTIFIC SIDE-LIGHTS 



he knows the function assigned to it in 

 his own intention. But as in making it 

 there are a thousand chips and fragments 

 of material which he casts aside, so in its 

 final use it often produces consequences and 

 results which he did not contemplate or 

 foresee. But in Nature all this is different. 

 Nature has no chips or fragments which she 

 does not put to use; and as on the way to 

 her apparent ends there are no incidents 

 which she did not foresee, so beyond those 

 ends there are no ulterior results which do 

 not open out into new firmaments of design. 

 Of nothing, therefore, can we say with even 

 the probability of truth that we see its final 

 cause; that is to say, its ultimate purpose. 

 All that we can ever see are the facts of ad- 

 justment and of function, and these consti- 

 tute not final but immediate purpose. But 

 a purpose is not less a purpose because 

 other purposes may lie beyond it. And not 

 only can we detect purpose in natural phe- 

 nomena, but . . . it is very often the 

 only thing about them which is intelligible 

 to us. The how is very often incomprehen- 

 sible where the why is apparent at a glance. 

 And be this observed, that when purpose is 

 perceived it is a " making plain " to a 

 higher faculty of the mind than the mere 

 sense of order. It is a making plain to rea- 

 son. It is the reduction of phenomena to 

 that order of thought which is the basis of 

 all other order in the works of man, and 

 which, he instinctively concludes, is the 

 basis also of all order in the works of Na- 

 ture. ARGYLL Reign of Law, ch. 2, p. 49. 

 (Burt.) 



434. CAUSE OF MIGRATION OF BIRDS 



Nesting-season the Controlling Factor 

 Bird Goes against Appearances. Why do 

 birds migrate? It is true that in temper- 

 ate and boreal regions the return of cold 

 weather robs them of their food, and they 

 retreat southward. But many, in fact most, 

 birds begin their southern journey long be- 

 fore the first fall frost. We have seen that 

 some species start as early as July and Au- 

 gust. Furthermore, there are many birds 

 that come to our Gulf and South Atlantic 

 States to nest, and when the breeding sea- 

 son is over they return to the tropics. Sure- 

 ly, a lower temperature cannot be said to 

 compel them to migrate. Even more re- 

 markable than the southward journey in the 

 fall is the northward journey in the spring. 

 Our birds leave their winter homes in the 

 tropics in the height of the tropical spring, 

 when insect and vegetable food is daily in- 

 creasing. They leave this land of plenty for 

 one from which the snows of winter have 

 barely disappeared, often coming so early 

 that unseasonable weather forces them to 

 retreat. 



I believe that the origin of this great pil- 

 grimage of countless millions of birds is to 

 be found in the existence of an annual nest- 

 ing-season. . . . There is good reason 

 for the belief that the necessity of securing 



a home in which their young could be reared 

 was, as it still is, the cause of migration. 

 CHAPMAN Bird-Life, ch. 4, p. 58. (A., 

 1900.) 



435. CAUSE, PHYSICAL, OF THE 

 ALPS All Earthly Energy Derived from the 

 Sun. And as I looked over this wondrous 

 scene towards Mont Blanc, the Grand Corn- 

 bin, the Dent Blanche, the Weisshorn, the 

 Dom, and the thousand lesser peaks which 

 seemed to join in celebration of the risen 

 day, I asked myself, as on previous occa- 

 sions: How was this colossal work per- 

 formed? Who chiseled these mighty and 

 picturesque masses out of a mere protuber- 

 ance of the earth? And the answer was at 

 hand. Ever young, ever mighty with the 

 vigor of a thousand worlds still within him 

 the real sculptor was even then climbing 

 up the eastern sky. It was he who raised 

 aloft the waters which cut out these ravines ; 

 it was he who planted the glaciers on the 

 mountain slopes, thus giving gravity a 

 plow to open out the valleys; and it is he 

 who, acting through the ages, will finally 

 lay low these mighty monuments, rolling 

 them gradually seaward 



Sowing the seeds of continents to be; 

 so that the people of an older earth may see 

 mold spread and corn wave over the hidden 

 rocks which at this moment bear the weight 

 of the Jungfrau. TYNDALL Hours of Exer- 

 cise in the Alps, ch. 17, p. 190. (A., 1898.) 



436. CAUSE, SAME, PRODUCES UN- 

 LIKE EFFECTS Dew and Frost Results of 

 Radiation. It is thus that dew is produced. 

 By the effect of nocturnal radiation bodies 

 exposed in the open air are cooled down, and 

 this cooling condenses on them the vapor of 

 water diffused in the atmosphere. Dew does 

 not descend from the sky, nor does it rise 

 from the earth. A light covering, a sheet of 

 paper, a cloud, is sufficient to check the ra- 

 diation and prevent dew, as it would pre- 

 vent frost. FLAMMARION Popular Astron- 

 omy, bk. ii, ch. 8, p. 175. (A.) 



437 . CAUSE SEEN IN LEAST EFFECT 



Motions of Stars Overwhelm Thought. 

 In the falling of a rock from a mountain- 

 head, in the shoot of an avalanche, in the 

 plunge of a cataract, we often see more im- 

 pressive illustrations of the power of grav- 

 ity than in the motions of the stars. When 

 the intellect has to intervene, and calcula- 

 tion is necessary to the building up of the 

 conception, the expansion of the feelings 

 ceases to be proport'ional to the magnitude 

 of the phenomena. TYNDALL Hours of Ex- 

 ercise in the Alps, ch. 20, p. 251. (A., 1898.) 



438- CAUSE, THE HIGHEST WORK 

 OF SCIENCE TO FIND Three Departments 

 of Scientific Study Observation, Experi- 

 ment, Theory. In the house of science are 

 many mansions, occupied by tenants of di- 

 verse kinds. Some of them execute with 

 painstaking fidelity the useful work of ob- 



