568 



THE POPULAR SCIENCE MONTHLY. 



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 varie- 

 ty 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 con- 

 ducing 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 con- 

 tracted since the first contact with Euro- 

 peans. " 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 con- 

 versed with many tattooed warriors of the 

 old school, who were invariably both physi- 

 cally 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 per- 

 nicious innovations, however, of modern 

 civilization among them being an immod- 

 erate 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 prin- 

 ciples, they told us that they believed in 

 nothing, and got fat on pork and potatoes." 



Water-Pnrificatlon of Sewage. The 



important part played by water in the oxi- 

 dation of sewage has been tested by experi- 

 ment, and may be accounted forby the quan- 

 tity of free oxygen that water usually con- 

 tains. The quantity that may be dissolved 

 is increased with reduction of the tempera- 

 ture. 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 equiv- 

 alent 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, 316 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 wa- 

 ter containing thirty-five per cent of sewage- 

 matter be allowed to flow for one mile, ex- 

 posed to the air, the whole of the sewage 

 would become oxidized. It has also been 

 estimated, by experiment, that a closed ves- 

 sel 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, al- 

 though the self-purifying power of the water 

 of the river is sometimes overtaxed, it still 

 retains the power of oxidizing sewage-mat- 

 ter ; but the question as to whether it has 

 the power of freeing itself from living bac- 

 teria still remains to be solved. 



The Identity of American Baces. 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 Mis- 

 sissippi 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 doc- 

 trine 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 anthro- 

 pologist, except in some very broad sense, 

 as, for example, that they belonged to the 

 human race, or that they inhabited one conti- 

 nent. In respect to mythologies, languages, 

 and institutions, there are, and have been, 



