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THE POPULAR SCIENCE MOXTHLY 



will notice broken egg-shells in the water, 

 and, on closer inspection, will observe wrig- 

 gling nondescripts on the bottom, neither 

 like fish nor eggs, but compounded of both. 

 When they once begin to appear, they come 

 in thousands, in millions, in myriads. The 

 young need more water, at this time, but 

 require less care ; yet still they must be 

 watched. The young fish may socn be 

 turned loose into the stream. 



If he is a salmon, after a few months' 

 preparation to strengthen his sinews and 

 test his power, he goes down to the sea, 

 there to dwell, and feed, and grow, gaining 

 wonderfully in size, drawing his sustenance 

 fiom the exhaustless storehouse of the world, 

 and coaling back to man, in a few months, 

 a magnificent embodiment of strength and 

 beauty, bringing to the lord of the universe 

 five or ten pounds of as delicious food as 

 ever delighted a gourmand's palate, or sat- 

 isfied a hungry man's stomach. If he is 

 only a trout, a younger brother of the glo- 

 rious family of the Salmonidcc^ he will lurk 

 about the bottom of some pond, or graze 

 some pebbly mountain-brook, and struggle 

 up to a half-pound or more before twelve 

 months shall have rolled over bis head. 



Heat evolved by Friction cf Icet Mr. 



A. Tylor, in a paper recently read before 

 the Geographical Society of London a sy- 

 nopsis of which was published in Nature 

 shows that heat evolved by friction of ice 

 upon ice is an important element in glacial 

 movement. By a simple apparatus he re- 

 duced ice to water in a temperature of 32, 

 at the rate of one and a quarter pound an 

 hour, by friction only of ice upon ice, the 

 pressure applied being but two pound to 

 the square inch. By simple evaporation, 

 the ice in the same temperature lost one- 

 quarter of a pound in the same time. 



In a temperature of 54 the production 

 of water under friction was three and a 

 quarter times greater than by simple melt- 

 ing when there was no friction. 



The actual heat evolved by friction of 

 ice upon ice is nearly the same as from oak 

 upon oak, when well lubricated. 



In the motion of glaciers great quanti- 

 ties of water are continually discharged, lu- 

 bricating the bottom. Surface-melting of 

 the ice Mr. Tylor censiders insufficient to 



produce it. The bottom of a glacier, with 

 its rasping under-surface of rock and sand, 

 slides, to some extent, upon the bottom, 

 and much heat is evolved in this way, but 

 in innumerable fractures of the sides of the 

 glaciers, of the surface-ice flowing on and 

 over bottom-ice, there are friction and attri- 

 tion, ice moving against ice, which melts 

 it, and the water percolates through the 

 fractures to the bottom. 



In great glaciers. the pressure is enor- 

 mous. With ice a mile thick it is half a 

 ton to the square inch, and the quantity of 

 water produced increased accordingly. 



Economic Value of the Sunflower. The 



common suuflower is a native of tropical 

 America, and there it sometimes attains the 

 extraordinary height, for an annual plant, 

 of twenty feet. It thrives in nearly every 

 region of the inhabitable globe. In the 

 south of Europe and in the northwest prov- 

 inces of India it is cultivated to a consid- 

 erable extent. In the latter country, sun- 

 flower-plantations are said to have a very 

 beneficial effect in promoting the healthful- 

 ness of regions infested by malarious fevers. 

 The seeds are valued as food for cattle and 

 poultry, and an oil may be expressed from 

 them which is scarcely inferior to olive-oil. 

 One acre of good land will produce about 

 fifty bushels of seed, each bushel yielding 

 a gallon of oil. The seeds are also used like 

 almonds for making soothing emulsions, 

 and, in some parts of Europe, a food for in- 

 fants is prepared from them. In tropical 

 America the Indians make bread of them. 

 The leaves are used as fodder for cattle, and 

 the stalks, when burned, yield large quanti- 

 ties of potash. , 



The plant called Jerusalem artichoke is 

 doubly misnamed ; it has as little to do with 

 the Holy City as the soup made from its 

 tuberous roots has to do with the Promised 

 Land, and yet the former is called Jerusa- 

 lem (from the Italian g'lrasole sunflower), 

 and the soup is called " Palestine," because 

 it contains " Jerusalem." It got the name 

 of " artichoke " from a resemblance in taste 

 between its tuber and the flower-receptacles 

 of the true artichoke, but it differs totally 

 from that plant in botanical characters. The 

 Jerusalem artichoke is a species of the sun- 

 flower, and, like all sunflowers, a native of 



