Page:Popular Science Monthly Volume 15.djvu/426

412 the right, across an ideal boundary; or it may be according to the velocity each atom chances to have when it approaches the boundary: if greater than a certain stated amount, it is to go the right; if less, to the left. This latter rule of assortment, carried into execution by the demon, disequalizes temperature, and undoes the natural diffusion of heat; the former undoes the natural diffusion of matter.

This looks to us like a somewhat ridiculous way of evading the real difficulties in the explanation of molecular motions and their effects. All nature is supposed to be filled with infinite swarms of absurd little microscopic imps, which are so omniscient that they direct the invisible and insensible movements by which the whole order of nature is determined and maintained. When men like Maxwell, of Cambridge, and Thomson, of Glasgow, lend their sanction to such a crude hypothetical fancy as that of little devils knocking and kicking the atoms this way and that, in order to explain the observed changes of natural phenomena, we may well ask, What next? This is a palpable case of contriving an artifice to explain a subject which yet leaves the subject more obscure than ever. There were difficulties enough with the molecules considered alone, but when complicated with another hypothetical order of beings the difficulties are redoubled, for we have now to explain the explanation. There is a great proneness to invent explanations which only remove the trouble one step further away. Sir William Thomson's hypothesis of the origin of terrestrial life by means of germs, brought to our planet from some unknown source by meteorites, is another example of explanations by assumptions, in which nothing is explained. There is a class of scientific men who feel it incumbent upon them to answer all questions. They do not seem to appreciate the fact that there are limits to our knowing, which had better be honestly acknowledged, instead of offering conjectures which are mere travesties of legitimate theory, and absurdities in science.

print an indignant letter from Mr. Bergh the philanthropist, denouncing one of our eminent ornithologists for saying that the English sparrows among us are interlopers, and, instead of being protected, should be left to shift for themselves, and be exposed to the raids of the street boys. We have a very high respect for Mr. Bergh and his mission, and have never been disposed to criticise his peculiarities or find fault with the way in which he has chosen to perform his duty. It is enough that such a man was greatly needed in the community, and it is not well to raise questions of taste, or to carp at mistakes committed in the performance of a disagreeable but most beneficent public service. We cordially approve of his practical work in protecting animals against the infliction of cruelty, whether from wantonness, carelessness, or insensate stupidity. But because Mr. Bergh's labors are important they ought to be maintained on proper grounds; though, judging from his letter, we should rather trust his instincts than his logic.

As regards the sparrows, Mr. Bergh seems not to recognize that they are at present under indictment, and, while we have no disposition to prejudge their case, it certainly is not to be settled on purely sentimental grounds. The question of their treatment depends upon whether or not they have become pests and nuisances. If it is true, as maintained by reputable naturalists and those who have observed their habits and history, that these birds are extremely prolific, hatching out several broods in the same season, and that, besides this, they have been so coddled and cared for as greatly to