852 



THE POPULAR SCIENCE MONTHLY. 



of the characters of bottoms and of the ex- 

 istence of any sediment or deposit ; of the 

 sources of sediment and the means of turn- 

 ing it away; the examination of the effects 

 of ice on the beds ; and the determination 

 of the density of the water, with special ref- 

 erence to the displacement of salt water by 

 fresh water from adjacent streams and riv- 

 ers. The plan of the work was to make 

 the investigation exhaustive over a limited 

 area, and extend it afterward as circum- 

 stances should permit. The results are 

 given in the present memoir. 



Explosive Materials. By M. P. E. Ber- 

 THELOT. Translated from the French by 

 Marcus Benjamin. New York : D. Van 

 Nostrand. (Science Series.) 1883. Pp. 

 180. Price, 50 cents. 

 In these lectures M. Berthelot has 

 summed up the results of his researches upon 

 explosives, and indicated the theory of their 

 action which they seem to him to warrant. 

 He is mainly concerned in considering how 

 an explosive is set in operation by means 

 of shock, and reaches the conclusion that in 

 all cases, whether the explosive influence be 

 propagated from particle to particle of an 

 explosive, or from one explosive body to an- 

 other, not in contact with it, the action con- 

 sists in the transformation of the energy of 

 the shock into heat. Before an explosion 

 can occur, some portion of the substance 

 must be i-aiscd to the temperature necessary 

 for the chemical reaction between its con- 

 stituents. That this temperature should be 

 reached, it is necessary that the impact be 

 sudden, as otherwise the transformation into 

 heat will take place so slowly that this heat 

 will be distributed through too great a mass 

 of material to raise its temperature to the 

 requisite point. The explosion of one par- 

 ticle of the substance produces a sudden 

 pressure, the energy of which, transformed 

 into heat, causes the next particle to explode, 

 and so on, the disturbance being thus prop- 

 agated through the entire mass of the ex- 

 plosive. M. Berthelot rejects the synchro- 

 nous theory of explosions by influence — 

 where a body is exploded by another at a 

 distance — of Abel, holding that the theory 

 of transformation of mechanical energy into 

 heat, and the retransformation of this into 

 mechanical energy, is competent to explain 

 all the phenomena. In discussing the con- 



ditions of maximum effect in explosion, he 

 points out the reason for the extremely low 

 velocity of propagation of the explosive wave 

 in gases, obtained by Bunsen, and shows that 

 this in reality moves with great rapidity. 



Mr. Benjamin's translation appears to be 

 accurate, and, despite occasional roughness, 

 is fairly well done. The volume contains 

 also a short historical sketch of gunpowder, 

 translated from the German of Karl Braun, 

 and a bibliography of works on explosives. 



The Ores of Leadville and their Modes 

 OF Occurrence, as illustrated in the 

 Morning and Evening Star Mines. 

 With a Chapter on the Methods of their 

 Extraction as practiced at those Mines. 

 By Louis D. Eicketts, B. S., Princeton, 

 N. J. Pp. 68, with Six Plates. 



The author, in order to comply with the 

 requirements of the W. S. Ward fellowship 

 in Economic Geology, in connection with 

 Princeton College, devoted four months at 

 Leadville to the study of the ores and their 

 modes of occurrence, and to the extraction 

 of the ores in the mines named in the title 

 we have cited. The result of this study is 

 given in the present paper, of which the 

 first part considers the scientific and the 

 second part the practical side. 



J. A. Berly's British, American, and Con- 

 tinental Electrical Directory and Ad- 

 vertiser. London : William Dawson 

 & Sons ; New York : George Gumming, 

 219 East Eighteenth Street. Pp. 664. 

 Price, $2.50. 



This volume, which embodies a record 

 of all the industries directly or indirectly 

 connected with electricity and magnetism, 

 and the names and addresses of manufac- 

 turers in England, the United States, Cana- 

 da, and the European Continent, is a valu- 

 able book of reference for all persons inter- 

 ested in electrical art. The increased size 

 and importance of this, the second edition, 

 over the volume published a year previously, 

 which was chiefly limited to England, is one 

 of many signs of the rapidly expanding de- 

 velopment of the applications of electricity. 

 Another similar sign is afforded by the va- 

 riety of trades — some of them appearing 

 at first sight only very remotely related to 

 electricity — ^that have been included within 

 its scope. The relation is nevertheless real, 

 for all these trades have been brought in to 



