176 



SCIENCE. 



[N. S. Vol. XXII. No. 554. 



this reason that on the title page the book is 

 said to be 'for hig'h schools and colleges.' 

 The clause 'for high schools' is probably 

 superfluous. If there are any high schools 

 in which a book of this grade can be success- 

 fully employed they are quite exceptional. 



Assuming that the book is exclusively for 

 collegiate students, or others of equivalent 

 maturity, it is very interesting and suggestive, 

 well up to date, and abundantly worthy of 

 cordial commendation. The first 212 pages 

 are taken up with the mechanics of solids and 

 fluids, each chapter being closed with a well- 

 selected list of books of reference. About 

 100 pages are then devoted to the phenomena 

 and laws of heat, including a brief chapter on 

 thermodynamics. Vibrations and waves re- 

 ceive quite full treatment, 80 pages being 

 devoted to this subject before that of sound 

 is mentioned. The analysis of sound, musical 

 instruments and musical compositions make 

 up three short chapters, about 27 pages in all. 

 To the subject of light 175 pages are given; 

 and to magnetism and electricity, 167 pages. 

 This may seem like a significant reaction 

 against the popular demand for utilitarianism 

 in physics, but it is not altogether surprising 

 that emphasis should be laid upon the phe- 

 nomena of heat and light in a laboratory 

 where Rowland's influence in behalf of pure 

 science was so long dominant. The theory of 

 electricity is brought out with much clear- 

 ness and in excellent style, while less than 

 five pages are devoted to dynamos and the 

 engineering applications of electricity to in- 

 dustry. 



A distinct defect in this otherwise excellent 

 book is the complete absence of illustrative 

 problems. The author may, perhaps, prefer 

 to avoid these as class-room tests, or he may 

 use them spontaneously and prefer not print- 

 ing problems, the solutions of which can be 

 transmitted down from class to class. The 

 majority of teachers are probably agreed that 

 the use of problems is indispensable in the 

 conveying of accurate ideas when the subject 

 is such as necessarily to imply the application 

 of mathematics, whether elermentary or ad- 

 vanced. 



Possibly a separate small volume of prob- 

 lems, as a supplement to the text-book, may 

 be forthcoming in the near future. If so it 

 will be welcomed by those who use this book 

 either for reference or in the hands of their 

 students. But, even as it stands, it is worthy 

 of the welcome which it c&n not fail to receive. 

 W. Le Conte Stevens. 



A Catalogue of North American Diptera. By 

 J. M. Aldrich. Smithsonian Miscellaneous 

 Collections, Vol. XLVL, No. 1444. 1905. 

 Pp. 1-680. 



The long-expected catalogue of North Amer- 

 ican diptera by Professor Aldrich has at last 

 appeared. It is the first work of its scope 

 to be published since Baron Osten Sacken's 

 catalogue which was issued by the Smithson- 

 ian in 1878. During the intervening quarter 

 of a' century the aspect of entomology in North 

 America has greatly changed, more especially 

 in the diptera, rendering the new catalogue 

 most welcome. 



The following remarks from Professor Aid- 

 rich's introduction show the relation which 

 exists between the two works : 



The great amount of work which has been done 

 on North American Diptera within the quarter 

 of a century has largely changed the face of the 

 subject. Hence the reader will probably observe, 

 especially at first, more of contrast than resem- 

 blance. The number of species has doubled; the 

 number of references to previously known species 

 has almost doubled; several families have been 

 monographed or revised, with more or less change 

 of nomenclature; along with this has gone the 

 publication of a multitude of smaller papers, 

 touching every family but one, and the larger 

 part of the genera. Under these conditions it 

 is inevitable that great changes should appear in 

 the new catalogue. 



The catalogue is rather unique among the 

 present lists of American insects in several 

 respects, all of them commendable. The 

 faunal limits are not restricted to the coun- 

 tries north of the Mexican boundary, but are 

 extended to include as far as Panama and the 

 West Indies on the south. This gives a much 

 more lasting value to the enumeration of spe- 

 cies than is possible when the banks of the 



