200 Scientific Intelligence. 



hyperbolic function. Mechanical strains also are most simply 

 expressed in this form. Hence the study of geological deforma- 

 tions always requires the use of these functions ; and it is for 

 this reason that the overseers of the XJ. S. Geological Survey, 

 Messrs. Becker and Van Orstrand, have prepared this most com- 

 plete and scholarly treatise. 



The book has a two-fold value. The tables, eight in number, 

 furnish everything that a worker with hyperbolic functions can 

 need, and they are preceded by an admirable exposition of the 

 theory of hyperbolic function. The subject is developed both 

 from an analytic and independently from a geometrical basis and 

 the relation to elliptic functions is described and also the con- 

 nection with the geometry of the pseudo sphere. An historical 

 sketch adds greatly to the breadth of view of the subject and 

 fifteen pages are given to formulas which the writers designate 

 as "those most likely to be needed by computers." 



This description should make it evident that the book furnishes 

 the most satisfactory treatise on this subject that has hitherto 

 been published. w. b. 



6. Bobbins^ Plane Trigonometry ; by Edward R. Robbins. 

 8vo, pp. xiii, 153. New York (American Book Company). — A 

 book well adapted for the secondary school course. It represents 

 the experience of a mature and careful teacher whose first object is 

 to get the essentials of the subject into the head of the average 

 boy as quickly and firmly as possible. The learner is introduced 

 to the solution of trigomometric equations sooner than usual, in 

 fact in the first chapter, but the treatment of identities is post- 

 poned until quite late for the reason that the author aims to give 

 his followers strength and courage for the assault of this formid- 

 able enemy of the weak trigonometer. The distinction between 

 an identity and an equation, however, is not explicitly stated. 



w. B. 



7. Experimental Dairy Bacteriology ; by H. L. Russell and 

 E. G. Hastings. 147 pages; illustrated. Boston 1909 (Ginn and 

 Co.). — The purpose of this book is to present an elementary course 

 in general dairy bacteriology. Though brief and somewhat 

 limited in its scope, it is complete in itself. The sources of milk 

 contamination, the biological changes that take place in milk, 

 with methods of identifying milk bacteria, the preservation of 

 milk, butter-making, cheese, and milk as a vehicle of disease, are 

 some of the important topics discussed. A thorough mastery of 

 the book should enable the student to pursue intelligently more 

 advanced work in connection with the problems of dairy bacteri- 

 ology or dairy manufactures. l. f. r. 



8. Bref och tSkirfvelser af och till Carl von Linne ; af Th. 

 M. Fries. Pp. iv, 342. Stockholm, 1909. — This third part of 

 the first volume of the correspondence of Linnaeus contains let- 

 ters Nos. 459 to 573 ; they are arranged alphabetically, accord- 

 ing to the names of the recipient or writer, from A to B. This 

 important publication is being carried on under the auspices of 

 the University of Upsala, and the librarian of the University 

 asks that any persons possessing letters of Linnaeus communicate 

 with him on the subject. 



