848 



SCIENCE 



[N. S. Vol. XXXIV. No. 885 



caused by the convectional currents in the 

 agitated air mass of a thunderstorm. Com- 

 paratively little attention has thus far been 

 paid to these short wave-length pressure oscil- 

 lations, and Mr. Palmer has extended our 

 knowledge of them by his examination of the 

 Blue Hill records. 



To have built and equipped, and to have 

 maintained for more than 25 years, an observ- 

 atory such as that on Blue Hill, which has 

 done so much real pioneer work of the highest 

 importance — surely this is a splendid contri- 

 bution to science. To Professor A. Lawrence 

 Eoteh American meteorology, indeed meteorol- 

 ogy everywhere, owes a debt which is year by 

 year becoming greater. E. DeC. Ward 



Harvard University 



Boch Minerals: Their Chemical and Physical 

 Characters and their Determination in Thin 

 Section. By Joseph P. Iddlsgs. Second 

 edition, revised and enlarged. New York, 

 John Wiley & Sons; London, Chapman & 

 Hall, Limited. 1911. Pp. 617. Cloth. 

 $5.00. 



That a second edition of Professor Iddings's 

 work has so soon been called for speaks well 

 for the growth of American petrography, 

 while the constant tendency manifested toward 

 a greater degree of refinement in methods 

 speaks- well for its future growth. 



The present edition, so far as its plan is 

 concerned, is practically identical with the 

 first, the important difference being the addi- 

 tion of such new material as brings the work 

 down to date. Upwards of 80 minerals are 

 described not included in the first edition; 

 " chiefly those occurring in pegma,tites and 

 segregated ores representing extremes of mag- 

 matic differentiation." Fifty-two figures are 

 added in the test, and 67 pages of descriptive 

 matter : a birefringence diagram is also added. 

 Incidental to this diagram and the colored 

 plate indicating the interference colors and 

 birefringence of the various minerals it may 

 well be asked if students entering upon the 

 study of micro-petrography are ever tested for 

 color blindness. It has often seemed to the 

 reviewer that sundry imperfect (rather than 



erroneous) descriptions which have been pub- 

 lished might be due to an inability on the 

 part of the worker to distinguish the various 

 colors, or at least to distinguish between their 

 relative values. 



The book, as in the previous edition, is di- 

 vided into two parts. Part First, Chapter 1, 

 being given up to a description of chemical 

 principles and characters, and is identical with 

 the edition of 1906. Chapter 2, dealing with 

 the physical principles and characters, is also 

 identical with the 1906 edition, and leaves 

 nothing to be desired in its method of presen- 

 tation. Chapter 3, on the optical properties, 

 deals with what is perhaps the most difficult 

 branch of the science for the student to master, 

 and is naturally the most difficult to handle in 

 a manner satisfactory to both worker and stu- 

 dent. It demands the knowledge and the ex- 

 perience of the advanced worker and yet the 

 teaching capacity of one who has not so far 

 outgrown his student days as to be unable to 

 appreciate the necessity of carefully detailed 

 presentation. With the advanced student this 

 chapter leaves little or nothing to be desired. 

 As, with the exception of a page and a haM 

 on pleochroic halos, it is identical with the 

 previous edition, nothing more need be said 

 here regarding it. 



Part 2 deals with the description of the 

 various rock minerals taken up in the order 

 of their chemical composition; alteration; 

 crystallographic characters ; optical properties ; 

 modes of occurrence; resemblances to other 

 minerals, and laboratory production. It is to 

 this portion of the book that the worker, how- 

 ever advanced, must have constant reference. 



Professor Iddings is recognized the world 

 over as an authority in all matters relating to 

 petrography, and words commendatory are 

 superfluous. The work is simply indispen- 

 sable to all petrographers. The method of 

 presentation is, however, naturally open to 

 discussion. To the reviewer it would seem 

 that for actual use and for purposes of ready 

 reference more discrimination might well have 

 been shown between minerals prominent as 

 rock constituents and those rare: between 



