Page:Popular Science Monthly Volume 38.djvu/297

Rh the condition of mathematical science in England is not fully satisfactory, there is more cause for congratulation at present than there has been at any time during the last one hundred and fifty years, and we are far removed from the state of affairs that existed before the days of Cayley and Sylvester. The author concluded with a plea for the study of the theory of numbers.

Value of Living Traditions.—According to Mr. J. G. Frazer, the author of a comparative study of religions, entitled the Golden Bough, the best source for knowledge of ancient folk-lore is among the people of the present. Every inquiry into the primitive religion of the Aryans, he says, "should either start from the superstitious beliefs and observances of the peasantry, or should at least be constantly checked and controlled by reference to them. Compared with the evidence afforded by living tradition, the testimony of ancient books on the subject of early religion is worth very little. . . . The mass of the people who do not read books remain unaffected by the mental revolution wrought by literature; and so it has come about that in Europe, at the present day, the superstitious beliefs and practices which have been handed down by word of mouth are generally of a far more archaic type than the religion depicted in the most ancient literature of the Aryan race."

The Magnetograph.—The magnetograph, the adaptability of which to use as a seismoscope has been tried by Prof. T. C. Mendenhall, is described by him as a system of magnetic needles, free to vibrate, and connected with a mirror that turns with the needles. It has long been noticed that an earthquake causes a considerable disturbance of the needles; and that this is not an effect of vibration is shown by the fact that a series of brass needles is not thus disturbed. It appears from the study of the magnetic records that there are two distinct vibrations, one due to solar influence and seeming to be dependent jointly on position and temperature; the other series were dependent on the relative position of the earth and the moon, and were therefore regarded as of a tidal nature; and the disturbances of the magnetic needle may be, and probably are, due to the stress of the earth's crust. The author mentioned as a remarkable fact that a periodic disturbance, smaller in amplitude than the thickness of the line recorded, could be positively and perfectly determined. This evidence that the lunar influence is due to variation of stress furnishes a clew to the explanation of the disturbances due to earthquakes. The stress to which the earth is then subjected causes an alteration in its magnetic condition which is recorded upon the sheet. It may therefore be possible to recognize an earthquake by disturbance of the magnetic needle, even when the motion is too small to be recognized by a seismoscope. It is a curious fact that it is supposed in Japan that an earthquake can be predicted by the vibrations of a loadstone.

The Natural Gas Supply.—The permanence of the natural gas supply was discussed in the American Association, which, meeting in the heart of the natural gas region, visited some of the more famous stations at Noblesville, Marion, Muncie, and Anderson, where the new fuel is used. President Goodale warned the people at Anderson against waste of the gas, because, he said, it will surely give out some day. Dr. Edward Orton affirmed in a paper in the Economic Section that the supply in the Indiana and Ohio fields is not only exhaustible, but is rapidly and surely being exhausted. It is not now being generated, and every foot that escapes to the surface leaves the quantity remaining for future use just so much smaller. This is proved by the fact that the pressure of the gas is steadily diminishing, the decrease having already amounted to thirty or forty per cent. Prof. P. H. Vander Weyde is of a different opinion. He believes that the gas is formed in much the same manner as water-gas; that the evolution of oxygen and hydrogen is constantly going on in the regions of the earth's interior, where the temperature of dissociation exists; and that when carbureted metals having great affinity for water are present within reach of the dissociated gases, they will be oxidized by the ascending oxygen, while the hydrogen will combine with the carbon to form hydrocarbons. Thus the process of generating the gas is going on all the