SCIENTIFIC SIDE-LIGHTS 



644 



ly present in the crops on the far-away 

 prairies from whence they came. . . . 



This plant first appeared in a locality 

 which was wooded and hilly, but in a few 

 seasons it reached the adjacent plains, where 

 it was rolled by the wind for miles and 

 miles, each year afterward invading new 

 territory. Within a dozen years it had 

 spread throughout South Dakota, had en- 

 tered North Dakota on the south, Iowa on 

 the north, and Nebraska on the east. Dur- 

 ing the next few years it spread with 

 marvelous rapidity, invading Minnesota, 

 Wisconsin, Colorado, Illinois, and Ohio. Its 

 progress was aided by the railroads that 

 carried the seed to many distant localities, 

 which quickly became new centers of 

 distribution. Presumably, the plant [the 

 Russian thistle or Russian cactus] will con- 

 tinue to spread by similar methods, and 

 within a few years will be present in most 

 of the United States. 



In the plains region of southeastern Rus- 

 sia this plant has long been known as a 

 noxious pest. On its account " the cultiva- 

 tion of crops has been abandoned over large 

 areas in some of the provinces near the 

 Caspian Sea." In our own West it has al- 

 ready caused damage amounting in a single 

 State to millions of dollars a year. WEED 

 Seed Travellers, ch. 1, p. 21. (G. & Co., 

 1899.) 



3190. SPREAD OF UNMOLESTED 

 SPECIES Reindeer Naturalized in Iceland 

 Rapid Increase from Small Beginning 

 Man Aids Nature by Destroying Destroyers. 

 As an example of the rapidity with which 

 a large tract may become peopled by the 

 offspring of a single pair of quadrupeds, it 

 may be mentioned that in the year 1773 

 thirteen reindeer were exported from Nor- 

 way, only three of which reached Iceland. 

 These were turned loose into the mountains 

 of GuldbringS Syssel, where they multiplied 

 so greatly, in the course of forty years, that 

 it was not uncommon to meet with herds, 

 consisting of from forty to one hundred, 

 in various districts. 



The reindeer, observes a modern writer, 

 is in Lapland a loser by his connection with 

 man, but Iceland will be this creature's 

 paradise. There is, in the interior, a tract 

 which Sir G. Mackenzie computes at not 

 less than forty thousand square miles, with- 

 out a single human habitation, and almost 

 entirely unknown to the natives themselves. 

 There are no wolves; the Icelanders will 

 keep out the bears, and the reindeer, being 

 almost unmolested by man, will have no 

 nemy whatever, unless it has brought with 

 it its own tormenting gadfly. LYELL Prin- 

 ciples of Geology, bk. iii, ch. 41, p. 686. 

 (A., 1854.) 



3191. SPRINGS EXPLAINED BY 

 ARTESIAN WELLS Lakes and Streams be- 

 neath the Earth. Much light has been 

 thrown, of late years, on the theory of 

 springs, by the boring of what are called 



by the French " Artesian wells," because 

 the method has long been known and prac- 

 tised in Artois; and it is now demonstrated 

 that there are sheets and in some places 

 currents of fresh water at various depths 

 in the earth. The instrument employed in 

 excavating these wells is a large auger, and 

 the cavity bored is usually from three to 

 four inches in diameter. If a hard rock 

 is met with it is first triturated by an iron 

 rod, and the materials, being thus reduced 

 to small fragments or powder, are readily 

 extracted. To hinder the sides of the well 

 from falling in, as also to prevent the 

 spreading of the ascending water in the 

 surrounding soil, a jointed pipe is intro- 

 duced, formed of wood in Artois, but in 

 other countries more commonly of metal. 

 It frequently happens that after passing 

 through hundreds of feet of retentive soils 

 a water-bearing stratum is at length pierced, 

 when the fluid immediately ascends to the 

 surface and flows over. The first rush of the 

 water up the tube is often violent, so that 

 for a time the water plays like a fountain, 

 and then, sinking, continues to flow over 

 tranquilly, or sometimes remains stationary 

 at a certain depth below the orifice of the 

 well. This spouting of the water in the 

 first instance is probably owing to the dis- 

 engagement of air and carbonic acid gas, for 

 both of these have been seen to bubble 

 up with the water. LYELL Principles of 

 Geology, bk. ii, ch. 16, p. 233. (A., 1854.) 



3192. SPUN GLASS FROM VOL- 

 CANO Pele's Hair Artistic Birds' Nests- 

 Man Imitates Nature's Product. Sometimes 

 the passage of [volcanic] steam through 

 a mass of molten glass produces large quan- 

 tities of a material resembling spun glass. 

 Small particles or shots of the glass are 

 carried into the air and leave behind them 

 thin, glassy filaments like a tail. At the 

 volcano of Kilauea, in Hawaii, this fila- 

 mentous volcanic glass is abundantly pro- 

 duced, and is known as " Pele's Hair " 

 Pele being the name of the goddess of the 

 mountain. Birds' nests are sometimes found 

 composed of this beautiful material. In 

 recent years an artificial substance simi- 

 lar to this Pele's hair has been exten- 

 sively manufactured bypassing jets of steam 

 through the molten slag of iron-furnaces; 

 it resembles cotton-wool, but is made up 

 of fine threads of glass, and is employed 

 for the packing of boilers and other pur- 

 poses. JUDD Volcanoes, ch. 4, p. 71. (A., 

 1899.) 



3193. SQUIRRELS PLANTING NUTS 

 Animals as Seed Distributers. Even be- 

 fore the arrival of frosts many of these 

 [nuts] are dropped by the aid of squirrels, 

 gray and red, which cut the stems with their 

 teeth. The leaves, with the help of the shift- 

 ing winds, gently cover the fruit, or some 

 portions of it, and make the best kind of pro- 

 tection from dry air and severe cold; and 

 they come just in the nick of time. Dame 



