March 2, 1900. ] 



SCIENCE, 



347 



pipes, and of preventing corrosion from elec- 

 trolysis are well discussed. Pumping systems 

 are treated more fully than usual ; this is a 

 step in the right direction, since about 75 per 

 cent, of the water works of the United States 

 are operated by this method, the gravity sys- 

 tems being largely confined to the large towns 

 on the Atlantic and Pacific States. The grow- 

 ing importance of water-supply engineering 

 may be clearly recognized from the fact that 

 the number of water works in the United Stateg 

 in 1898 was about 1600, while in 1897, it was 

 about 3200. The book is well illustrated, clearly 

 written, and will be a valuable aid to all who 

 are planning or operating public water sup- 

 plies. 



The increasing interest in securing purity of 

 water-supplies is not only evidenced by the cir- 

 cumstance that the book of Mr. Hazen has 

 reached its third edition in less than four years, 

 but also by the construction of sand filter beds 

 at seventeen American towns and cities in the 

 last decade. During the same period more than 

 one hundred others have installed mechanical 

 filtration plants. No fact in sanitary engineer- 

 ing is, indeed, more fully established than that 

 the death rate from typhoid fever is materially 

 lowered by filtration, and the present interest 

 of the public gives hope that the time is not far 

 distant when the cities of the United States may 

 take rank with London, Berlin, Vienna, and 

 Amsterdam in freedom from that disease. Mr. 

 Hazen is a high authority on this subject, and, 

 although an ad-vocate of the system of slow fil- 

 tration through sand beds, his book treats also 

 of the more rapid system of mechanical filters, 

 which iu many cases may be installed at less 

 expense. The present edition gives the results 

 of the recent experiments at Louisville, Pitts- 

 burg, and Cincinnati, and also valuable informa- 

 tion regarding the filter beds of several Euro- 

 pean cities. Statistics of both systems of filtra- 

 tion are presented ia tabular form. These show 

 that the slow sand system is used by cities hav- 

 ing an aggregate population of 21,400,000, of 

 of which 10,200,000 are in Great Britain and 

 260,000 in the United States. The aggregate 

 population using mechanical filters in the United 

 States and Canada is nearly 1,600,000, while 

 this system is practically unemployed in other 



countries. At the present time only about one- 

 tenth of the cities and towns of the United 

 States have filtered water supplies. The book 

 of Mr. Hazen, as well as the large plant recently 

 built at Albany, N. Y., under his supervision, 

 will have much influence in inducing other cities 

 to inaugurate effective methods for the purifica- 

 tion of their water supplies. 



Mansfield Meeriman. 



California Mines and Minerals. Published by 

 the California Miners' Association, under the 

 direction of Edward H. Benjamin, Secre- 

 tary for the California Meeting of the Amer- 

 ican Institute of Mining Engineers. San 

 Francisco, Calif 1899. Vol. 8. Pp. 450. 

 This treatise upon the mines and mining of 

 California is dedicated to the members of the 

 American Institute of Mining Engineers ' as 

 a souvenir of their visit to California ' in Sep- 

 tember and October, 1899 ; but it is a vastly 

 more important and valuable work than the 

 usual ' souvenir. ' It constitutes a very valuable 

 treatise upon the great industry to which it is 

 devoted and is full of important information, 

 valuable historical facts and industrial statistics. 

 It is a large volume, handsomely printed, ex- 

 tensively and well illustrated, well made and 

 substantially bound. Its market value is stated 

 to be five dollars and the munificence of the 

 Californian is well exhibited in the fact that a 

 copy was supplied to every member of the 

 visiting Society. 



The contents consist of thirty-five papers by 

 well-informed writers and often the ablest in 

 their respective departments. In these chap- 

 ters are described the topography, geology and 

 mineral deposits of the various mining counties 

 of the State, the methods of working, the sta- 

 tistics of production, and the special conditions 

 of exploitation and development of the more 

 interesting fields, especially those in which the 

 precious metals are produced in largest quan- 

 tity. Regarding the most important products, 

 gold and silver, copper, borax, bituminous and 

 asphaltic rock, quicksilver, and petroleum, the 

 ground is remarkably well covered. We note 

 that the output of silver has less value than 

 that of petroleum and that quicksilver has fifty 

 per cent, larger value than the former. 



