126 TRANSACTIONS iSqQ-'OO 



country, they invited professors from European universities to 

 come over and fill the chairs in their seats of learning ; they in- 

 vited engineers and architects from Europe and America to come 

 and build their railways and erect their public buildings; and these 

 gentlemen residing in Japan, occasionally felt their houses shaken 

 by earthquakes, and at not infrequent intervals the engineers and 

 architects saw the fruits of their labors wrecked b}^ seismic dis- 

 turbances. Naturally an intense interest was awakened and a 

 scientific investigation of seismdc phenomena was soon in progress. 



Prior to 1861 Robert Mallet had studied the velocity of earth 

 waves produced artificially by exploding charges of gunpowder 

 varying between 25 and 12,000 lbs, and somewhat similar methods 

 were employed by Gray, Milne and others in Japan. Professor 

 Milne says : "The shakings were first obtained from the fall 

 from heights up to about thirty feet of a ball approaching a ton 

 in weight and subsequently by the explosion of dynamite and 

 gunpowder in bore holes. The resulting vibrations longitudinal, 

 transverse, and vertical, were recorded at a series of stations so ar- 

 ranged in electrical connection that the time of any vibrations 

 could be noted to a small fraction of a second. These experiments 

 explained many phenomena observed in earthquake disturbances, 

 and directed attention to others the existence of which was for 

 the first time rendered probable. The velocit}^ of propagation of 

 wave motion evidently increased with the intensity of the initial 

 disturbance ; it was greater for vertical and normal than for 

 transverse waves ; whilst motion was propagated more rapidly to 

 stations that were near an origin than to stations at some distance 

 from the same. The period of the movements increased as the 

 disturbance died out or as it radiated. It was surmised years ago 

 that violent earthquakes occurring at any point on the earth's 

 surface might, if suitable and sufficiently delicate instruments 

 were used, be recorded at any other point ; and it has since been 

 abundantly proved that the surmise was correct. 



To Prof. Thos. Gray and John Milne belongs the credit of 

 having devised a seismograph that will record the tremors pro- 

 pagated to far off lands, 



In the spring of 1897 a letter was received from the chairman 

 of the B. A. A. S., requesting the co-operation of the Toronto 



