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THE POPULAR SCIENCE MONTHLY. 



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 diffu- 

 sion of heat; the former undoes the natural 

 diffusion of matter. 



This looks to us like a somewhat 

 ridiculous way of evading the real diffi- 

 culties 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 insen- 

 sible movements by which the whole 

 order of nature is determined and 

 maintained. When men like Maxwell, 

 of Cambridge, and Thomson, of Glas- 

 gow, 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 natu- 

 ral phenomena, we may well ask, What 

 next ? This is a palpable case of con- 

 triving an artifice to explain a subject 

 which yet leaves the subject more ob- 

 scure than ever. There were difficul- 

 ties enough with the molecules consid- 

 ered 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 ex- 

 plained. There is a class ot 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, in- 



stead of offering conjectures which are 

 mere travesties of legitimate theory, 

 and absurdities in science. 



MR. BERGH AND THE SPARROWS. 



We print an indignant letter from 

 Mr. Bergh the philanthropist, denounc- 

 ing 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 dis- 

 posed 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 per- 

 formance of a disagreeable but most 

 beneficent public service. We cordial- 

 ly 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 impor- 

 tant they ought to be maintained on 

 proper grounds ; though, judging from 

 his letter, we should rather trust his in- 

 stincts 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 set- 

 tled on purely sentimental grounds. 

 The question of their treatment de- 

 pends upon whether or not they have 

 become pests and nuisances. If it is 

 true, as maintained by reputable natu- 

 ralists 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 



