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THE POPULAR SCIENCE MONTHLY. 



lines of least resistance, and the deed is 

 done. In this way many young people, who 

 were supposed to be the models of moral 

 perfection, have, to their own surprise as 

 well as that of their friends, suddenly fallen. 

 In such cases the evil desire, which had be- 

 fore been kept within the limits of the body, 

 is simply continued and completed in the 

 outward world. With what force come to 

 us the words, "Blessed are the pure in 

 heart " ! and, again, " Whatsoever things 

 are true, honorable, just, pure, lovely, and of 

 good report, whatever is praiseworthy and 

 virtuous, think on these things." Physiologi- 

 cal psychology gives the strongest emphasis 

 to these old moral precepts. Nerve paths 

 used constantly in true thinking and noble 

 sentiment become the lines of least resist- 

 ance, while those for ignoble thought and 

 feeling become like unused, neglected roads 

 difficult to travel. It thus becomes con- 

 stitutionally easy to live nobly, and organic- 

 ally difficult to do wrong. In the second 

 place, when evil thoughts are aroused they 

 are at once automatically negatived (inhib- 

 ited) by good impulses, and without any ac- 

 tion of the will there is an instinctive recoil 

 from the evil suggestion. 



Bacteriology and Public Health. In 



connection with the relation between bac- 

 teriology and public health, Prof. Frankland 

 referred, in the discussion in the British As- 

 sociation, to investigations by himself and 

 others on the purification of drinking waters 

 by subsidence, nitration, and precipitation. 

 He pointed out that great misconception pre- 

 vailed as to the real value of water analyses, 

 the object of which was to show whether a 

 water was liable to become a source of dan- 

 ger at any time, and not whether it was ac- 

 tually dangerous at a particular moment. 

 Recent methods had, however, made it pos- 

 sible to detect the special bacteria of typhoid 

 and cholera when present in a drinking 

 water. Contrary to the common belief, bac- 

 teria could retain their vitality in ordinary 

 water for weeks, while the spores were not 

 destroyed for months ; but different species 

 varied in this respect. Sewage was best 

 treated by intermittent nitration through 

 soil. This process removed the bacteria 

 more rapidly and completely than it removed 

 dissolved organic matter. Later investiga- 



tions had confirmed the early observations 

 of Downes and Blount on the susceptibility 

 of bacteria to the action of light, and it ap- 

 peared that the well-known disinfecting 

 power of the sun's rays was due to the fact 

 that they actually destroyed bacteria and 

 their spores, the rate of destruction depend- 

 ing on the nature of the organism and the 

 condition in which it was placed. 



Coal Dust and Explosions. In a paper 

 on Explosions in Coal Mines, Prof. H. B. 

 Dixon said that the statement that explo- 

 sions do not travel through damp parts of a 

 mine has been confirmed, and that it is 

 practicable to localize and isolate explosions 

 by always keeping certain sections of the 

 mine damp. Recent experiments by Mr. 

 Hall and by an Austrian committee agree 

 with some earlier experiments in showing 

 that different coal dusts vary enormously in 

 their degree of inflammability, and that mix- 

 tures of some dusts with air are violently 

 explosive if ignited by means of a large 

 flame. The great variation in the properties 

 of coal dusts probably accounts for the dif- 

 ference between the reports from different 

 districts. Whether it is true that coal dust 

 and air alone are explosive, or that the pres- 

 ence of small quantities of fire damp is es- 

 sential, must be shown by further investiga- 

 tions on the nature of the dust from differ- 

 ent mines, the degree of danger attaching to 

 the use of different explosives, and the effi- 

 ciency of various methods of laying the dust 

 in mines. 



Education and " Short Cats to Utopia." 



The question whether the general education 

 of the masses is on the whole a good thing 

 is under discussion in the English papers. 

 A writer in one of them attributes to it 

 " that wonderful readiness to believe in 

 short cuts to Utopia" which is one of the 

 marked and unmistakable features of our 

 day. The Spectator disputes this, and cites 

 the evidence of history as being all the other 

 way. " The most desperate attempt ever 

 made to realize heaven on earth by a short 

 cut was made by the followers of John of 

 Leyden, who were for the most part as de- 

 void of what is now called education as the 

 beasts of the field. There never was such a 

 dream of the short cut to Utopia as was 



