i9o6.] SEE— THE CAUSE OF EARTHQUAKES. 399 



tially from a volcano, only in pultonic rocks having been injected, instead of 

 volcanic matter having been ejected, this appears to me an interesting circum- 

 stance; for we may infer from it as provable, that in the elevation of a 

 mountain chain, two or more of the parallel lines forming it may be upraised 

 and injected within the same geological period." 



§ 59- Views of Professor Milne. 



Professor Milne has recently expressed views of somewhat 

 similar character, many of which agree closely with those reached in 

 this paper. In the recent Bakerian Lecture before the Royal Society, 

 he says : 



" But if, instead of confining our attention to a relationship between 

 earthquakes, we consider the question of the relief of volcanic strain, many 

 illustrations may be adduced which indicate a close connection between such 

 activities. For example, all the known volcanic eruptions which have oc- 

 curred in the Antilles, from the first which took place in 1692, have been 

 heralded or closely accompanied by large earthquakes in that region, but 

 more frequently by like disturbances in neighboring rock-folds, particularly 

 that of the Cordilleras. This was notably the case in 1902. On x\pril 19 

 of that year an unus.ually large earthquake devastated cities in Guatemala. 

 Small local shocks were felt in the West Indies, and on April 25 it was no- 

 ticed that steam was escaping from the crater on Mont Pelee, in Martinique. 

 These activities continued to increase until May 8, when they terminated 

 with terrific explosions, submarine disturbances, and the devastation of great 

 portions of the islands of Martinique and St. Vincent. 



"The last illustration of hypogene relationship between these regions 

 occurred on Januarv 31 of the present year. On that date a heavy earth- 

 quake originated off the mouth of the Esmeralda River, in Columbia. Sea- 

 waves inundated the coast, islands sank, and a volcano erupted. The news- 

 papers of February 2 announced that cables between Jamaica and Puerto 

 Rico had been interrupted, and on later dates it was reported that severe 

 shocks had been felt among the West Indian islands, that six or seven sub- 

 marine cables had been broken, and that Mont Pelee and La Soufriere, in 

 St. Vincent, were again active." ^ 



We have quoted these views of Humboldt, Darwin and Milne 

 in order to exhibit fairly the beliefs of all these great investigators 

 in the development or the possibility of the development of seismic 

 action at a distance when a disturbance is once started. 



§ 60. Teleseismic disturbances. 



From the theory developed in this paper w^e take is that when a 

 severe earthquake is started at one place the tremors may cause 

 disturbances to spread into neighboring regions or to break out at 

 a distant point if the conditions of the steam pressure underlying 



^ Proc. Roy. Soc, Vol. yy, 1906, p. 374. 



