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THE POPULAR SCIENCE MONTHLY. 



fourth. In the four succeeding chapters, 

 the forms of energy constituting heat, light, 

 sound, and electricity are considered, with 

 such illustrative examples as exhibit the 

 essential features of each group. A brief 

 summary of the principles of machines 

 forms the closing chapter. A new feature 

 of the book is a review at the end of each 

 chapter, consisting of principles and topics, 

 and a number of problems. Simple restate- 

 ment of principles in the order of the pre- 

 vious discussion has been avoided, with the 

 object of showing the truths enunciated in 

 new relations and with added force. The 

 text throughout is fully illustrated. 



Eminent Israelites of the Nineteenth 

 Century. By Henry Samuel Morais. 

 Philadelphia : Edward Stern & Co. 

 1880. Pp. 371. Price, $2. 



The careers of the hundred Jews, whose 

 portraits Mr. Morais has presented in this 

 volume, speak much for the inherent vital- 

 ity and power of a race so long proscribed. 

 The sketches are brief, much too brief to do 

 justice to many of their subjects, but they 

 are in the main judicious and are full of 

 interest. The labors of these eminent He- 

 brews take a wide range. Literature, the- 

 ology, music, philanthropy, statesmanship, 

 and commercial pursuits all have their rep- 

 resentatives, many of whom have achieved 

 not only distinction, but positions of the 

 very first rank. They are as diverse in their 

 nationalities as in the character of their la- 

 bors, coming as they do from all European 

 states, as well as from America. The rec- 

 ord as a whole is one with which Jews have 

 reason to be gratified, while it is interesting 

 and instructive to a wider circle. 



Manual of Hydraulic ilixiNO, for the Use 

 OP THE Practical Miner. By T. F. Van 

 Wagenen, E. M. New York: D. Van 

 Nostrand. 1880. Pp. 93. 



Placer-mining, the author states, is, 

 when economically conducted, as certain of 

 good returns as any ordinary avocation. 

 Auriferous gravel deposits are very exten- 

 sive on the Pacific coast, and, as the plant 

 necessary is comparatively inexpensive, the 

 miner has a wide field for remunerative 

 work. He must, however, conduct his oper- 

 ations with a knowledge of the nature of 



his materials and the most efficient way 

 of working them to secure success. Most 

 miners at present engaged in hydraulic min- 

 ing, Mr. Van Wagenen says, have but slight 

 knowledge of physics, and are more or less 

 rusty in their arithmetic, so that many er- 

 rors are made in construction and operation, 

 which prove costly experiments. He has 

 therefore attempted, in this little manual, 

 to give, in a clear and concise form, the 

 information needed to avoid such errors. 

 Among the subjects briefly treated are the 

 use of decimals; the methods of finding 

 areas and volumes ; the pressure of water 

 when at rest, and its flow through orifices 

 and flumes ; the proper method of construct- 

 ing flumes, their grades, size of nozzles, etc. 

 Tables of square and fifth roots of the num- 

 bers commonly entering into the miner's 

 calculations are given at the end of the 

 book. 



Deep-Sea Sounding and Dredging. A De- 

 scription and Discussion of the Methods 

 and Appliances used on board the Coast 

 and Geodetic Survey Steamer Blake. By 

 Charles D. Sigsbee, Lieutenant-Com- 

 mander U. S. Navy. Washington : Gov- 

 ernment Printing-Office. 1880. Pp.208. 



Lieutenant-Commander Sigsbee was in 

 charge of the Blake for the four years 

 from December, 1874, and during this time 

 prosecuted extensive researches relative to 

 the condition of the deep-sea bottom. Dur- 

 ing the winter of 1874-75 soundings were 

 made off the mouth of the Mississippi Riv- 

 er, the total number of miles being 2,505. 

 Nearly as many miles of soundings were 

 taken in the Gulf of Mexico in the summer 

 of 1875, and in the winter of that and the 

 next year a system of east and west lines 

 was run across the great bank west of the 

 Florida Peninsula. Others were run on the 

 northern portion of the bank, and a number 

 from the delta of the Mississippi out to sea, 

 closing with a line from the South Pass to 

 the Yucatan Bank, and one from Alacran 

 Reef to Tortugas. The remaining years 

 were devoted to further soundings in this 

 portion of the waters of the American coast. 

 The Blake was very thoroughly fitted out 

 for her work. Her party was one of the 

 first to use piano-forte wire for deep-sea 

 dredging and trawling, and the experience 

 with it showed it to be much better than 



