. Earthquakes and other earth movements. Earthquakes. 58 EARTHQUAKES. The object of tbe experiment was to find the nature of the vibrations produced in the crust of the earth by such a blow, the velocity of transmission through this comparatively soft material, the effect of hills and excava- tions in cutting off such disturbances, and the law accord- ing to which the amplitude of the vibrations diminishes with the distance from the source. A considerable variety of apparatus was used during these experiments, but the most reliable results were obtained from the records of a rolling sphere sei
. Earthquakes and other earth movements. Earthquakes. 58 EARTHQUAKES. The object of tbe experiment was to find the nature of the vibrations produced in the crust of the earth by such a blow, the velocity of transmission through this comparatively soft material, the effect of hills and excava- tions in cutting off such disturbances, and the law accord- ing to which the amplitude of the vibrations diminishes with the distance from the source. A considerable variety of apparatus was used during these experiments, but the most reliable results were obtained from the records of a rolling sphere seismograph, which wrote the vibrations on a stationary plate, and from the records' of two bracket seismographs, similar to Pro- fessor Ewing's horizontal lever seismographs, which gave a record of the vibrations as two rectangular components on a moving plate of smoked Fia. 10. The general result as to the nature of the disturbance was that two distinct sets of vibrations were set up by the blow. In one set the direction of motion was along a line joining the point of observation with the point from which the disturbance emanated ; in the other set the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Milne, John, 1850-1913. New York, D. Appleton and company
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