Reviews — Seismological Society of Japan. 369 



surface. Had the mountain been left very hollow at the termination 

 of the series of eruptions which formed it, its density would have 

 been much greater than Mr. Mendenhall's experiments have proved 

 it to be. 



Mr. Paul contributes the abstract of a treatise on the effect of 

 Eailroad trains in transmitting vibrations through the ground. This 

 paper is extremely interesting in conveying an idea of the immense 

 distance to which earth vibrations may be transmitted. The object 

 of the investigation which is chronicled by the writer was to deter- 

 mine a site for a United States Naval Observatory, where observa- 

 tions could be conducted without serious interference. The brief 

 abstract published by the Society merits full citation. We have 

 only space, however, to say that, by observing through a powerful 

 telescope the surface of mercury lying in a dish placed at a mile's 

 distance from him, the experimentalist at his post on a railway line 

 can note the effect of the vibration of a passing train upon the subtle 

 mineral, as accurately as if he were peering into the vessel itself. 

 This wonderful telescopic feat almost eclipses the fact that it demon- 

 strates, namely, that the earth's surface is sufficiently elastic to 

 transmit comparatively the small vibration caused by a passing 

 vehicle to a great — perhaps to an indefinite — distance. 



Professor E wing's paper, the fourth in the volume, is an abstract 

 of one read before the Asiatic Society in December, 1880. It de- 

 scribes a seismograph which appears to have been constructed with 

 scientific accuracy and to have done good work in recording the 

 tremors which it has experienced. 



The fifth and last paper is from the pen of Professor Milne, and 

 is on the great Peruvian earthquake of May, 1877. It contains a 

 tabulation of all the phenomena connected with a series of abnormal 

 sea- waves which swept across the Pacific in the month in question, 

 and the effects of which were slightly experienced in the harbour 

 of Yokohama, and further north, as at Hakodate, where it did con- 

 siderable damage. A sea-wave, originating in seismic spasm, takes 

 about twenty-five hours to travel from South America to Japan. 

 But electricity rides still more speedily ; and it might be well for the 

 Government of Japan to make arrangements with the controllers of 

 the South American Republics to telegraph hither prompt accounts 

 of seismic or volcanic disasters which may occur in their vicinity. 



Mr. Milne has introduced into his essay a series of calculations 

 whereby he estimates the point (between Pabalon de Pica and 

 Iquique, and nearer the former than the latter place) where the 

 great earthquake originated. As several of the methods employed 

 by the writer in his attempts to locate the point of origin of terres- 

 trial disturbances appear to be new and at the same time perfectly 

 rational, this portion of the treatise will probably prove a valuable 

 addition to the science of seismology. The writer also makes some 

 notes on previous earthquake-provoked waves which have crossed 

 the Pacific in this direction, with calculations of the Ocean's depth, 

 whereon, it must be remembered, depends, in a great degree, the 

 velocity of wave movement. His calculations made on many 



DECADE II. — YOL. IX. — NO. VIII. 24 



