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THE POPULAR SCIENCE MONTHLY. 



the debatable region ; and the opinion of a 

 number of geographers and travelers who 

 do not agree with the majority. Moreover, 

 the Brahmapootra does not need the San- 

 po, and the Irrawaddy does. Mr. Gordon's 

 views were strongly controverted by General 

 J. T. Walker and other experts in Indo- 

 Chinese geography. 



Distribution of an Insect Species. The 



Anonia plexippus, an American butterfly, 

 is now engaged in distributing itself over 

 the world. It is extending itself both east- 

 wardly and westwardly. Its natural range 

 appears to be from the Hudson Bay Ter- 

 ritory to the Amazon and Bolivia ; but some 

 thirty or forty years ago it began to wan- 

 der. It has established itself and become 

 abundant in the Sandwich Islands. The 

 first specimens were observed in the Mar- 

 quesas Islands, by a Roman Catholic mis- 

 sionary, about 1860. It is now the com- 

 monest butterfly there. It has appeared in 

 the Society, Cook, Harvey, Samoan, Friendly, 

 and Feejee Islands, the North Island of New 

 Zealand, Norfolk Island, Australia, Tasma- 

 nia, the New Hebrides, Solomon Islands, 

 New Guinea, Celebes, and Java ; and it was 

 abundant in New Caledonia a few years 

 ago, but has become more rare there. In 

 the eastward direction it has made its way 

 to the West Indies, has been long estab- 

 lished in Bermuda, furnished one specimen 

 in the Azores in 1864, was found in South 

 Wales in 1876, at La Vendee the only 

 specimen yet found on the Continent of 

 Europe in 1877, and in Kent in 1881. 



Uses of Liqnid Carbonic Acid. The 



liquefaction of carbonic acid was at first a 

 mere scientific curiosity, and only a few are 

 probably as yet aware that it is much more. 

 But a German firm, Messrs. Raydt & Kun- 

 heim, have devised an apparatus for pro- 

 ducing the liquid, and are producing it in 

 large quantities for industrial purposes. It 

 is used for charging beer in the cask ; and 

 in the manufacture of seltzer-waters the gas 

 is more easily and effectively introduced 

 from a vessel containing the liquid than in 

 the old-fashioned way. It has been found 

 very valuable for the service of fire-extin- 

 guishers. The Krupps, of Essen, use it for 

 producing compact castings. For this pur- 



pose the mold is closed as soon as the metal 

 has been introduced, and is connected by a 

 valve with the vessel containing the liquid 

 acid, the pressure of the gas from which is 

 augmented by heating it in a salt-water 

 bath. The Krupps have found that a heat 

 of 360 will give the colossal pressure of 

 twelve hundred atmospheres. Another ap- 

 plication of the liquid proposed by Dr. Raydt 

 is to the raising of sunken ships by means 

 of the gas from it. Compressed air has 

 long been employed for this purpose, but it 

 requires a costly apparatus that may be done 

 away with if liquefied carbonic acid is sub- 

 stituted for it. In some experiments made 

 at Kiel, a stone weighing three hundred 

 quintals was raised, by means of a balloon 

 filled with carbonic acid, from a depth of 

 thirty feet to the surface of the water in 

 eight minutes. 



Travel by Balloon. Mr. William Pole 

 insists, in '* Nature," that the feasibility of 

 balloon navigation has been made very 

 highly probable by the recent French ex- 

 periments. M. Tissandier, in 1883, obtained 

 with his dirigible balloon a velocity of nine 

 miles an hour. The French military authori- 

 ties then commissioned two of their officers, 

 Messrs. Renard and Krebs, to work the prob- 

 lem further out. They obtained an independ- 

 ent velocity through the air of upward of 

 thirteen miles an hour, with a balloon which 

 was managed, steered, and guided with the 

 greatest ease, and was made to return to its 

 starting-point in defiance of the wind. Care- 

 ful calculations, made according to the rules 

 of M. Dupuy de Lome and Professor Ran- 

 kine, of the resistance afforded by the air 

 and the efficiency of the screw-propeller, 

 show that the attainment of considerably 

 higher speeds is perfectly practicable. A 

 balloon of fifty feet diameter, for example, 

 would carry power sufficient to give a speed 

 of upward of twenty miles an hour, and still 

 leave a considerable buoyancy disposable. 



Colors of Swedish Eyes. Professor 

 Wittrock read a paper before the Swedish 

 Anthropological Society on the investigations 

 into the hereditability of the color of the 

 eyes, which he had undertaken at the in- 

 stance of Professor Alphonse de Candolle. 

 These results differed from those which 



