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428 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 Sanpo, 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 eastwardly and westwardly. Its natural range appears to be from the Hudson Bay Territory to the Amazon and Bolivia; but some thirty or forty years ago it began to wander. It has established itself and become abundant in the Sandwich Islands. The first specimens were observed in the Marquesas Islands, by a Roman Catholic missionary, about 1860. It is now the commonest butterfly there. It has appeared in the Society, Cook, Harvey, Samoan, Friendly, and Feejee Islands, the North Island of New Zealand, Norfolk Island, Australia, Tasmania, 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 established in Bermuda, furnished one specimen in the Azores in 1864, was found in South Wales in 1876, at La Vendée—the only specimen yet found on the Continent of Europe—in 1877, and in Kent in 1881.

Uses of Liquid 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 & Kunheim, have devised an apparatus for producing 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-extinguishers. The Krupps, of Essen, use it for producing compact castings. For this purpose 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 application 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 substituted 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 experiments. M. Tissandier, in 1883, obtained with his dirigible balloon a velocity of nine miles an hour. The French military authorities then commissioned two of their officers, Messrs. Renard and Krebs, to work the problem further out. They obtained an independent 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. Careful calculations, made according to the rules of M. Dupuy de Lôme and Professor Rankine, 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 instance of Professor Alphonse de Candolle. These results differed from those which