591 



SCIENTIFIC SIDE-LIGHTS 



Revolution 

 Rivers 



even as the afrit was summoned by the 

 rubbing of Aladdin's lamp? Thus the ques- 

 tion first asKed twenty-two hundred years 

 before was renewed, and now impressed with 

 greater urgency than ever upon the newly 

 awakened human intellect [in the sixteenth 

 century]. PARK BENJAMIN Intellectual Rise 

 in Electricity, ch. 9, p. 252. (J. W., 1898.) 



2921. RIGHT WINS ITS OWN CON- 

 QUEST Will Has Only To Hold It Steadily at 

 the Front. When our impulsive feeling is 

 hot . . . it is hard to hold the right 

 idea steadily enough before the attention 

 to let it exert its adequate effects. Whether 

 it be stimulative or inhibitive, it is too rea- 

 sonable for us; and the more instinctive 

 passional propensity then tends to extrude 

 it from our consideration. We shy away 

 from the thought of it. It twinkles and 

 goes out the moment it appears in the mar- 

 gin of our consciousness, and we need a reso- 

 lute effort of voluntary attention to drag it 

 into the focus of the field, and to keep it 

 there long enough for its associative and 

 motor effects to be exerted. . . . Once 

 brought, however, in this way to the center 

 of the field of consciousness and held there, 

 the reasonable idea will exert these effects 

 inevitably; for the laws of connection be- 

 tween our consciousness and our nervous 

 system provide for the action then taking 

 place. Our moral effort, properly so called, 

 terminates in our holding fast to the ap- 

 propriate idea. JAMES Talks to Teachers, 

 ch. 15, p. 186. (H. H. & Co., 1900.) 



2922. RISE AND FALL OF ANCIENT 

 LANDS Forests Submerged New Vegetation 

 Succeeding (Ps. cvii, 33, 35). In some of 

 the deeper coal-beds there is a regular alter- 

 nation between layers of coal and layers 

 of sand or clay; in certain localities as 

 many as ten, twelve, and even fifteen coal- 

 beds have been found alternating with as 

 many deposits of clay or mud or sand; and 

 in some instances, where the trunks of the 

 trees are hollow and have been left stand- 

 ing erect, they are filled to the brim, or to 

 the height of the next layer of deposits, with 

 the materials that have been swept over 

 them. Upon this set of deposits comes a 

 new bed of coal with the remains of a new 

 forest, and above this again a layer of ma- 

 terials left by a second freshet, and so on 

 through a number of alternate strata. It 

 is evident from these facts that there has 

 been a succession of forests, one above 

 another, but that in the intervals of their 

 growth great floods have poured over the 

 marshes, bringing with them all kinds of 

 loose materials, such as sand, pebbles, clay, 

 mud, lime, etc., which, as the freshets sub- 

 sided, settled down over the coal, filling 

 not only the spaces between such trees as 

 remained standing, but even the hollow 

 trunks of the trees themselves. AGASSIZ 

 Geological Sketches, ser. i, ch. 3, p. 84. (H. 

 M. & Co., 1896.) 



2923. RISE IN GRADE OF LIFE 



Insect Life Shows the Gradation. Take a 

 homely and very familar example, that of 

 the branch of articulates. Naturalists di- 

 vide this branch into three classes Insects, 

 Crustacea, and Worms; and most of them 

 tell you that worms are lowest, Crustacea 

 next in rank, and that insects stand highest, 

 while others have placed the Crustacea at 

 the head of the group. -We may well ask 

 why. Why does an insect stand above a 

 crustacean, or vice versa; why is a grass- 

 hopper or a butterfly structurally superior 

 to a lobster or a shrimp? . . . But when 

 we study the gradual development of the 

 insect, and find that in its earliest stages 

 it is wormlike, in its second, or chrysalis 

 stage, it is crustacean-like, and only in its 

 final completion it assumes the character of 

 a perfect insect, we have a simple natural 

 scale by which to estimate the comparative 

 rank of these animals. AGASSIZ Journey in 

 Brazil, ch. 1, p. 21. (H. M. & Co.) 



2924. RIVERS CLARIFIED BY 

 PASSING THROUGH LAKES Purity of 

 Niagara's Torrent The Rhone Flows Clear 

 from Lake of Geneva. The fact that bodies 

 of standing water retain the mineral matter 

 brought to them in suspension is illustrated 

 more or less perfectly in nearly every lake 

 and pond, and even by ephemeral pools by 

 the wayside, but is especially marked in 

 great seas like those drained by the St. Law- 

 rence. During storms all of. the streams 

 pouring into the upper Laiirentian lakes, 

 from the surface drainage of the land, are 

 brown and heavy with mud, but the water 

 rushing over Niagara remains of the same 

 deep greenish-blue tint season after season 

 and year after year. Niagara River, above 

 the falls, and the St. Lawrence, are surface 

 streams, because their clear waters have 

 but slight power of corrasion; it is for this 

 reason that during the centuries they have 

 occupied their present channels they have 

 not materially deepened them. 



In the case of lakes fed by the turbid 

 waters from glaciers the part they play as 

 settling-basins is even more strikingly 

 shown than in the instances just cited. 

 Lake Geneva, Switzerland, fed by the silt- 

 laden waters of the Rhone, is discolored 

 for several miles from where the river 

 enters, but when the waters leave the lake 

 and again start on their journey they are 

 wonderfully clear. An abundance of similar 

 illustrations is furnished by the glacial- 

 fed lakes of the Sierra Nevada and Cas- 

 cade mountains and by some of the 

 numerous lakes on the head waters of the 

 Yukon. RUSSELL Lakes of North America, 

 ch. 2, p. 39. (G. & Co., 1895.) 



2925. RIVERS IN THEIR WILD 



STATE Maps Change from Year to Year. 

 The greatest changes are shown by rivers 

 in their wild state that is, where they di- 

 vide into numerous arms and may be said 

 to dissolve into separate veins, as may be 



