Page:Popular Science Monthly Volume 44.djvu/880

862 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 before 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." Physiological 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 resistance, while those for ignoble thought and feeling become like unused, neglected roads—difficult to travel. It thus becomes constitutionally easy to live nobly, and organically difficult to do wrong. In the second place, when evil thoughts are aroused they are at once automatically negatived (inhibited) by good impulses, and without any action of the will there is an instinctive recoil from the evil suggestion.

Bacteriology and Public Health.—In connection with the relation between bacteriology and public health, Prof. Frankland referred, in the discussion in the British Association, to investigations by himself and others on the purification of drinking waters by subsidence, filtration, and precipitation. He pointed out that great misconception prevailed 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 danger at any time, and not whether it was actually dangerous at a particular moment. Recent methods had, however, made it possible to detect the special bacteria of typhoid and cholera when present in a drinking water. Contrary to the common belief, bacteria 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 filtration through soil. This process removed the bacteria more rapidly and completely than it removed dissolved organic matter. Later investigations had confirmed the early observations of Downes and Blount on the susceptibility of bacteria to the action of light, and it appeared 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 depending 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 explosions 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 m their degree of inflammability, and that mixtures 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 difference between the reports from different districts. Whether it is true that coal dust and air alone are explosive, or that the presence of small quantities of fire damp is essential, must be shown by further investigations on the nature of the dust from different mines, the degree of danger attaching to the use of different explosives, and the efficiency of various methods of laying the dust in mines.

Education and "Short Cuts 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 devoid 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