Page:Popular Science Monthly Volume 12.djvu/763

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To the Editor of the Popular Science Monthly.

IN your February number, Dr. J. R. Black assumes to correct Dr. Niemeyer's statement that the night-air of large cities is less noxious than the stirred-up air of the daytime, and he does so with a degree of confidence that seems to imply that there can be no such thing as doubting that he speaks ex cathedra.

Now, Dr. Black evidently believes that the insalubrity of city air depends upon the amount of non-respirable gases that may be diffused into the respirable ones; and is wholly independent of the condensible effluvia of the vaporous kind, or of the organic germ-dust that the heat and stir of the day may keep suspended, but would settle with the cooling and quiet of the night.

Now, while the precise application of the law to cities has not been made before, perhaps, in your journal, the teaching which inevitably leads to it has been abundant, and from unquestionable authority, so that, if Dr. Black wishes to correct so fatal an error as he charges this to be, he is very late with his solicitude. One lecture of Tyndall's, published by you, devoted much detail to the experiments of the professor, in his attempts to bottle a sterilized infusion in the laboratory of the Royal Institution, in air he had attempted to sterilize there, and explaining that he did succeed in a special chamber elsewhere. If, as Dr. Black would imply, noxious effluvia obey the law of diffusion of permanent gases, how comes it that they specially hover over low marshes and putrefying cesspools, while the ascent of a mountain of considerable elevation carries us above malaria and aërial infection, and often above bacterial decay?

A recent experiment of Tyndall's was to sterilize a bottle of infusion and open it upon the brink of a precipice, and, after contact with the air, recork it, to observe whether the infusion retained its sterility or not. He found the air germless. The experiment was made to test this identical question of the settling of ferment-germs.

Pasteur tried similar experiments, ascending to high points in Paris, bottling and comparing the air so bottled in putrefactive power with air bottled upon Mont Blanc, and with the air of the streets of Paris, always with the result of finding the air of the street levels more laden with micronymes than that obtained at considerable elevations. Upon the Western Plains, before civilization had scattered its filth, laden with zymogens, meats hung up in the air, even in midsummer, would keep sweet for days. The emigrants of 1849, in crossing the Plains, were surprised to find often the carcasses of dead animals of a previous caravan, drying-up viscera, and all without decay. This is easily explained on the germ-theory; without, it is inexplicable. If Dr. Black has any evidence that the germ-theory of decay and zymotic diseases is untenable, he should presently submit it, for, to my thinking, the world is only waiting to hear from Dr. Charlton Bastian, when the testimony and argument will be declared closed.

C. W. Johnson.
Atchison, Kansas, February 20, 1878.



We extract the following from a private letter of a Swiss archæologist:

"In The Popular Science Monthly of last November, page 121, I read that in Colorado on ruins more than 500 years old, probably much older, there are found drawings of horses. Can this be correct? I know there are found fossil remains of horses in America, but I know also that the horse was totally extinct in America at the time of its discovery by the Spaniards. Ruins on which drawings of horses are found must, therefore, be more recent than the discovery of America by the Spaniards. The well-preserved cedar-wood indicates that the ruins cannot be as old as the fossil horse. From the fact that no signs of a door are visible in the outer walls, and the ingress was from the top, I conclude that these ruins must have been built by the Pueblo Indians, or an allied race. I believe the Pueblo Indians to be the last remains of a more highly-civilized race, perhaps identical with the mound-builders, and would attribute to the same race the antiquities of Arizona. They have been almost exterminated by the later invasions of very distinct tribes. The aborigines of America did not know in 1492 the use of iron. That a skeleton in a Utah mound (page 123, ibid.) would have been found with a huge iron weapon in the right hand is therefore, for me, quite incredible. Also the occurrence of wheat in the same mound and of bones of sheep in the Colorado ruins. Except