Rivers 

 Rocks 



SCIENTIFIC SIDE-LIGHTS 



592 



witnessed wherever a stream plunges from 

 the mountains immediately into a plain. 

 The Rhine runs wild as it enters the upper 

 Rhine plateaux, the Bode does the same at 

 the north foot of the Harz, the Inn as it 

 forsakes the Alps. Throughout such regions 

 scarcely a year elapses without one arm or 

 another disappearing, while other branches 

 are formed. Successive maps, therefore, show 

 very different pictures of the stream. 

 PETJCK Oberflachenbau,Anleitung zurLandes- 

 und Volksforschung, p. 29. (Translated for 

 Scientific Side-Lights.) 



2926. RIVERS IN THE OCEAN 



The Gulf Stream. The narrow currents or 

 true oceanic rivers which traverse the sea 

 bring warm water into higher and cold 

 water into lower latitudes. To the first 

 class belongs the celebrated Gulf Stream, 

 which was known to Anghiera, and more 

 especially to Sir Humphrey Gilbert in the 

 sixteenth century. Its first impulse and 

 origin are to be sought to the south of the 

 Cape of Good Hope; after a long circuit it 

 pours itself from the Caribbean Sea and 

 the Mexican Gulf through the Straits of 

 the Bahamas, and, following a course from 

 south-southwest to north-northeast, con- 

 tinues to recede from the shores of the 

 United States, until, further deflected to 

 the eastward by the banks of Newfound- 

 land, it approaches the European coasts, 

 frequently throwing a quantity of tropical 

 seeds (Mimosa scandens, Guilandina Ion- 

 due, Dolichos urens) on the shores of Ire- 

 land, the Hebrides, and Norway. The 

 northeastern prolongation tends to mitigate 

 the cold of the ocean, and to ameliorate the 

 climate on the most northern extremity of 

 Scandinavia. HTJMBOLDT Cosmos, vol. i, p. 

 307. (H., 1897.) 



2927. RIVERS LIFTED BY THE 



SUN Heat Restored in Downward Flow. 

 Late discoveries have taught us that winds 

 and rivers have their definite thermal 

 values, and that, in order to produce their 

 motion, an equivalent amount of solar heat 

 has been consumed. While they exist as 

 winds and rivers, the heat expended in pro- 

 ducing them has ceased to exist, being con- 

 verted into mechanical motion; but when 

 that motion is arrested, the heat which 

 produced it is restored. A river, in descend- 

 ing from an elevation of 7,720 feet, gen- 

 erates an amount of heat competent to 

 augment its own temperature 10 F., and 

 this amount of heat was abstracted from the 

 sun, in order to lift the matter of the river 

 to the elevation from which it falls. As 

 long as the river continues on the heights, 

 whether in the solid form as a glacier or in 

 the liquid form as a lake, the heat expended 

 by the sun in lifting it has disappeared 

 from the universe. It has been consumed 

 in the act of lifting. But at the moment 

 that the river starts upon its downward 

 course, and encounters the resistance of its 

 bed, the heat expended in its elevation be- 



gins to be restored. The mental eye, in- 

 deed, can follow the emission from its 

 source; through the ether as vibratory mo- 

 tion; to the ocean, where it ceases to be 

 vibration, and assumes the potential form, 

 among the molecules of aqueous vapor; to 

 the mountain-top, where the heat absorbed 

 in vaporization is given out in condensa- 

 tion, while that expended by the sun in 

 lifting the water to that elevation is still 

 unrestored. This we find paid back to the last 

 unit: by the friction along the river's bed; 

 at the bottom of the cascades where the 

 plunge of the torrent is suddenly arrested; 

 in the warmth of the machinery turned by 

 the river; in the spark from the millstone; 

 beneath the crusher of the miner [or] in 

 the Alpine sawmill. TYNDALL Heat a Mode 

 of Motion, lect. 17, p. 527. (A., 1900.) 



2928. RIVERS OF ICE The Glacier 

 Flows Like a Stream No Sharp Line Di- 

 vides Different States of Matter. As might 

 be expected from these varied phenomena, it 

 has been found that there is no such sharp 

 line of distinction between the various 

 states of matter as is popularly supposed; 

 some of the properties which are charac- 

 teristic of matter in one state being present 

 in a less degree in other states. Viscous 

 bodies, for example, often present phe- 

 nomena characteristic of both solids and 

 fluids. Sealing-wax, pitch, and ice are all 

 brittle at low temperatures, resembling in 

 this respect such solids as glass and stone; 

 but they are at the very same time fluid, if 

 time enough is allowed to exhibit the phe- 

 nomenon. This is seen in the motion of 

 glaciers, which move in every respect like 

 true fluids, even to the middle of the stream 

 flowing quicker than the sides, and the top 

 than the bottom. Eddies and whirls occur 

 in glaciers as in rivers, and also upward 

 and downward motion, so that rocks torn 

 off the glacier floor may be carried upward 

 and deposited on surfaces hundreds of feet 

 above their place of origin. WALLACE The 

 Wonderful Century, ch. 7, p. 55. (D. M. & 

 Co., 1899.) 



2929. RIVERS, TRANSPORTING 

 POWER OF Earth Carried from Mountains 

 to Sea. The quantity of mud held in sus- 

 pension by the waters of the Ganges and 

 Brahmaputra is found, as might be ex- 

 pected, to exceed that of any of the rivers 

 alluded to in this or the preceding chap- 

 ters; for, in the first place, their feeders 

 flow from mountains of unrivaled altitude, 

 and do not clear themselves in any lakes, 

 as does the Rhine in the Lake of Constance, 

 or the Rhone in that of Geneva. And, sec- 

 ondly, their whole course is nearer the 

 equator than that of the Mississippi or any 

 great river respecting which careful experi- 

 ments have been made to determine the 

 quantity of its water and earthy contents. 

 The fall of rain, moreover, as we have be- 

 fore seen, is excessive on the southern 

 flanks of the first range of mountains which 



