Page:Popular Science Monthly Volume 27.djvu/586

568 volcanoes in the world, its landscape is also crowned by the snowy peaks of some of the highest mountains in Australasia. With these important features, it is endowed with scenery of the grandest order, and with a climate unsurpassed for its variety and healthfulness. According to Mr. Nicholls, the Maori people in New Zealand are decreasing; for, while in Captain Cook's time they numbered more than 100,000 souls, in 1881 the number had decreased to 44,099. The three principal diseases conducing to the decay of the race are phthisis, chronic asthma, and scrofula, the first two being principally brought about, Mr. Nicholls believes, by a half-savage, half-civilized mode of life, and the latter from maladies contracted since the first contact with Europeans. "It is, however, clear that there are a large number of natives yet distributed throughout the King Country, and among them are to be found, as of old, some of the finest specimens of the human race. A change of life, however, so different from that followed by their forefathers, has brought about a considerable alteration for the worse among the rising population, and, although during my journey I met and conversed with many tattooed warriors of the old school, who were invariably both physically and mentally superior to the younger natives, it was clear that this splendid type of savage will soon become a matter of the past. I found the natives living much in their primitive style, one of the most pernicious innovations, however, of modern civilization among them being an immoderate use of tobacco among both old and young." At Ruakaka, in the heart of the mountainous forest region, the Maories were found living in the same primitive way as in the time of Cook, and, "when we questioned them as to their religious principles, they told us that they believed in nothing, and got fat on pork and potatoes."

Water-Purification of Sewage.—The important part played by water in the oxidation of sewage has been tested by experiment, and may be accounted for by the quantity of free oxygen that water usually contains. The quantity that may be dissolved is increased with reduction of the temperature. At the summer temperature of 70° Fahr., water contains 1·8 cubic inch, and at the winter temperature of 45°, 2·2 cubic inches, of oxygen per gallon, which is equivalent to four or five cubic inches per foot. From calculations based upon these data, it will be seen that at a temperature of 70° there are 2·58 tons, and at the temperature of 45°, 3·16 tons, of oxygen in every 10,000,000 cubic feet of water. This shows a difference of more than half a ton per cubic foot between these two temperatures. It has been calculated that if a volume of water containing thirty-five per cent of sewage matter be allowed to flow for one mile, exposed to the air, the whole of the sewage would become oxidized. It has also been estimated, by experiment, that a closed vessel containing water, with five per cent of sewage, gives only thirty-two per cent of aeration on the fourth day, as compared with eighty-four per cent on the day when it is introduced into the vessel. The results of these experiments tend to show that, although the self-purifying power of the water of the river is sometimes overtaxed, it still retains the power of oxidizing sewage-matter; but the question as to whether it has the power of freeing itself from living bacteria still remains to be solved.

The Identity of American Races.—J. W. Powell writes to "Science," pertinently to its review of the Marquis de Nadaillac's "Prehistoric America," that, in his opinion, "there has never been presented one item of evidence that the mound-builders were a people of culture superior to that of the tribes that inhabited the valley of the Mississippi a hundred years ago. The evidence is complete that those tribes have built mounds within the historic period; and no mounds or earthworks have been discovered superior in structure or contents to those known to have been built in historic times." Nevertheless, Mr. Powell considers the doctrine of "the identity of all peoples that ever inhabited the American Continent up to the advent of Europeans" one that is not and can not be held by any intelligent anthropologist, except in some very broad sense, as, for example, that they belonged to the human race, or that they inhabited one continent. In respect to mythologies, languages, and institutions, there are, and have been,