Reviews — Ground-tuater and Springs. 275 



of the volcanic displays are as follows : (1) illumination over Mauna 

 Loa, (2) earthquakes, (3) discharge from Kilauea, (4) landslide, 

 (5) great sea-waves, (6) eruption and flow of lava from near 

 Mauna Loa to Kilauea. In 1868 the lava gushed out from an 

 elevation of 5,600 feet and along an earthquake fissure a mile in 

 length, that coincided in the lower part of its course with the western 

 edge of the plateau. It is remarked that the earthquakes belong to 

 the class denominated volcanic rather than tectonic, and that from the 

 destructive effects of the latter Hawaii is immune. The quaking is 

 produced by the passage beneath the surface of lava which is 

 endeavouring to escape. Eventually vertical fissures are formed, 

 and the lava wells out. In another paper Mr. A. C. Lawson gives 

 a description with illustrations of "Recent Fault Scarps at Genoa, 

 Nevada ". 



XI. — Gkotjnd-water and Spkings. 



Grundwassbb, tjnd Quellen. By Dr.h.c. Hans Hofee von 

 Heimhalt. pp. xi + 135, with 51 figures in the text. Eraun- 

 schweig : Friedr. Vieweg & Sohn, 1912. Price 4 marks. 



rpHE provision and maintenance of a plentiful supply of good 

 JL drinking water is a question of primary importance to the 

 inhabitants of every town or city, or any place where men crowd 

 closely together, and a satisfactory answer to it calls for the aid 

 of the chemist to test the purity of the water, and of the engineer 

 to pump and convey it, and, in the first instance, of the geologist to 

 determine the best and most suitable source of the desired supply. 

 We must not forget, too, that springs which are not ordinarily 

 potable may have valuable medicinal uses. The subject is one 

 that lies somewhat outside the scope of ordinary textbooks on 

 geology, and Dr. Hofer von Heimhalt has by this book met a distinct 

 gap in scientific literature ; the treatment, while adequate, is simple 

 in style, and the avoidance of unnecessary technicality renders the 

 book suitable to a wide circle of readers. 



The book opens with a short section on the hardness of water and 

 the factors which govern the suitability of water for drinking 

 purposes. The next deals with the more or less devious paths by 

 which the moisture present in the atmosphere ultimately finds its 

 way by condensation and infiltration underground in the shape of 

 water, and the author points out how large a part mountains play 

 in feeding the underground supply by causing an ample precipitation 

 of moisture. In the third section he discusses at some length the 

 various types into which underground water may be classified 

 according to the formation of the strata carrying it, and the change 

 produced in the water-level by steady pumping. Incidentally the 

 danger of removing water from an unstable sand layer is emphasized; 

 a danger, moreover, that has to be reckoned with even when the 

 object of the boring is not water, but one of the shallow or deep 

 tunnels with which we are so familiar in London. The excellent 

 diagrams with which the text is liberally illustrated show clearly 

 that, although haphazard well-sinking may often be successful in 



