274 Reviews — Earthquakes and Volcanoes. 



In cliapter iv is given a brief account of the geological history of 

 British volcanoes. Here some advances have been made since the 

 publication in 1897 of Sir A. Geikie's great work on the subject, to 

 which the author rightly gives prominence. At Brent Tor lavas of 

 Upper Devonian and Carboniferous age are now recognized by the 

 Geological Survey {Geology of Tavistock, etc., 1911, p. 51); 

 Mr. Barker's views on the Sgurr of Eigg might have been explained 

 a little more fully than in a footnote, and his researches on the 

 Tertiary igneous rocks of Skye should have been mentioned by the 

 author when dealing with the controversy between Professor Judd 

 and Sir A. Geikie. He need not then perhaps have abstained from 

 any expression of opinion on the matter. 



Chapter v, on the distribution of volcanoes, is followed by a final 

 chapter on the theories of volcanoes. Here, as in the previous 

 criticisms we have ventured to make, we must bear in mind the 

 author's reminder that his " aim in writing has not been the 

 examination room". At the same time he has left some of his 

 general conclusions as they were written for the first edition in 1898, 

 though admitting that "since then important advances have been 

 made". In treating of the origin of volcanoes he alludes to earth 

 movements as probably "potent agents in causing molten rock to 

 change its position " ; he maintains that the expansive form of steam 

 is "a prime factor in the explosive phenomena", and that though 

 much of the water may have been added at a late stage in the history 

 of an eruption, " A'et water may also have been present in the magma 

 from the very first, or may have gained access to it at a much earlier 

 stage in its history." While referring to Dr. A. Brun's view that 

 water plays but a small part in the explosive phenomeua of volcanic 

 eruptions, reference should have been made also to the important 

 volume on The Natural History of Igneous Rocks, by Mr. Harker 

 (1909), who argues that there is sufficient water in the deep-seated 

 molten rocks to explain the aqueous phenomena displayed in volcanic 

 eruptions. Nevertheless, we agree with the author that it is difficult 

 to account for the phenomena " without supposing a marked and 

 local increase of the water originally present in the magma". 



X . — Earthquakes. 



rilHE Bulletin of the Seismological Society of America (vol. ii, 

 JL No. 3, 1912) contains, among other articles, an historical 

 account of the " Great Earthquakes in the Island of Haiti ", 

 by Mr. J. Soberer. Particulars relating to " The Hawaiian Earth- 

 quakes of 1868 " are given by Mr. C. H. Hitchcock, now a resident 

 at Honolulu. The disturbances have occurred in association with 

 eruptions from Mauna Loa and Kilaxiea, and it is pointed out that 

 there is a sympathetic connexion between the two volcanoes. 

 Although the lava from one issues at an altitude of 12,000 feet and 

 from the other at 3,500 feet, synchronous eruptions have taken place 

 when the pressure of lava was most potent, and they have been 

 accompanied by strenuous earthquakes. In the light of present 

 knowledge, Mr. Hitchcock states that the chief events in the history 



