Febbuaey 15, 1895.] 



SCIENCE. 



187 



quantity of coke-oven tar, though constantly 

 increasing, probably does not at present ex- 

 ceed 50,000 tons. It maj' be expected, how- 

 ever, that witli the more general introduc- 

 tion of electricity for lighting purposes and 

 the consequent diminution of the supply of 

 gas tar, the coke-oven tar will eventually 

 become the main source of our aromatic 

 ' hydrocarbons." To this it should be added 

 that the increasmg use of ' water-gas,' in 

 this country at least, is decreasing the sup- 

 ply of coal-tar, so that the time is certainly 

 approaching when it will pay to collect the 

 tar from the coke-ovens. 



The translator expresses the hope " that 

 this work will be found valuable not only 

 to the technical chemist, but also to the 

 dyer, analyst, merchant, patent agent, etc., 

 and in fact to every one concerned with the 

 production, handling, or use of the coal-tar 

 coloui-s." His hope is undoubtedly well 

 founded. He might have added the patent 

 lawyers, many of whom have learned to 

 rattle oft" their ' ortho,' ' meta,' ' jmra' with 

 a facility that would put many a modest 

 chemist to the blush. Ir.\ Remsen. 



Elementary Lei<son.s in Electricity and Magnet- 

 ism. Sylvanus P. Thompson. K^ewYork, 

 Macmillan&Co. 1894. Pp.628. Price, 

 81.40. 



The fii-st edition of this book appeared in 

 1881. It at once became immensely popu- 

 lar, and deservedly so, on both sides of the 

 Atlantic. The author combined in a rare 

 degree the three principal requisites for the 

 preparation of a good text-book. He was 

 himself a widely known scholar and investi- 

 gator in the department of science specially 

 treated ; he was more than ordinarily ac- 

 complished in the art of exposition, and he 

 was an experienced and successful teacher. 

 His possession of these qualifications in un- 

 diminished magnitude is evidenced in the 

 preparation of this new edition now offered 

 to the public, which is the original work in 

 plan, but entirely revised and largelv re- 



written, with an enlargement of scope suffi- 

 cient to embrace the importivnt additions to 

 the science which have l)een made during 

 the past fifteen yeai-s. To enable this to be 

 done without undesirable condensation, the 

 size of the volume has been somewhat in- 

 creased. Indeed, one of the larger merits 

 of the plan of the book is to be found in the 

 conscientious retention of the long known 

 and well estal)lished principles and facts of 

 the science, to neglect which for the newer 

 and more novel developments is a tempta- 

 tion to which too mauj' authors of text-books 

 in physical science have yielded. While 

 retaining all essential 'fundamentals,' Pro- 

 fessor Thompson has found place for the 

 presentation of all of the essentials of recent 

 discovery, and while this has been done with 

 conciseness it has also been done with that 

 clearness and logical appropriateness for 

 which the wiitings of this author are justly 

 celebrated. The wonderful results of the 

 study of alternating currents and alternating 

 current machinery are well presented in this 

 edition, as are recent advances in both theory 

 and experiment due to Hertz, Fitzgerald, 

 Boltzmann, Lodge and others. At the end 

 is an excellent series of questions, classified 

 as to the chapters of the books to which 

 they refer, which cannot fail to add much 

 to the value of the book in use, especially 

 for those who study without an instructor. 

 In fact, as an ' all around ' elementarj- text- 

 book in electricity and magnetism it will be 

 difficult to find another in the English lan- 

 guage that is superior or even equal to this. 



T. C. M. 

 The Birds of Eastern Pennsylvania and New 

 Jersey, prepared under the direction of the Del- 

 aware Valley Ornithological Club. Bj' WiT- 

 MER Stone. Philadelphia, 1894. 8°, pp. 

 vii-i-185. 



Eastern Pennsylvania has hmg been a 

 favorite field for lovers of birds. Audubon, 

 Wilson, Nuttall. Cassin, Peale, Woodliouse, 

 Gambel, Bonaparte. Heerman, Haldeman, 



