328 EECOR]) OF SCIENCE FOR 1887 AND 1888. 



It is a. necessary consequence to tiie late development of the science 

 that a great amount of detailed study be given to rock structure and com- 

 position as revealed not only by the microscope and chemical analyses, but 

 by their field relations as well, and that therefore the published papers 

 should be given up largely to what may- seem to the outsider the dry, 

 uninteresting and perhaps immaterial iteration and re-iteration of de- 

 tails in even their most minute forms. To enter upon a discussion or 

 to note even in abstract the contents of all these iDapers would be use- 

 less and out of place here, and in the body of this paper I shall strive to 

 show only the general tendencies of these, to point out if possible the 

 ultimate conclusions towards which they seem to be leading, leaving a 

 majority of the papers to be enumerated in the bibliugraphy. 



NEW PUBLICATIONS. 



Early in 1887 there appeared the second volumeof the second edition 

 of Professor Eoseubusch's works on petrography, entitled "THikrosko- 

 pische Physiographie der massigen Gesteiue," the first volume, " Mikro- 

 skopische Physiographic der Mineralien und Gesteine," having appeared 

 in 1885. The entire work comprises 1,541 pages, with 32 full-page plates 

 showing microstructures of rocks and minerals, and 177 wood-cuts in the 

 text. The two volumes together form a most accurate and exhaustive 

 resume of the sumof petrographic knowledge up to date of issue, and their 

 appearance marks a decided epoch in the history of the science of petrol- 

 ogy. Under the title of " Hiilfstabellen zur mikroskopischen Mineralbes- 

 timmung in Gesteinen," the same authority has issued a compact little 

 work giving in tabular form the crystallographic, optical, and, general 

 physical and chemical properties of all the common rock-forming min- 

 erals. It is of interest to note that upw ards of one hundred and seventy 

 varieties are recognized. The arrangement is admirable, and the book 

 can not fail to be of great assistance to all students and workers. An 

 event second in importance only to the issue of Professor Kosenbusch's 

 work has been the translation and abridgment of volume i by i\Ir. J. 

 P. Iddings, ot the TJ. S. Geological Survey, audits publication by Wiley 

 & Co., New York. As prior to this there was no comprehensive work 

 on the subject in the Englisli language, the importance to English- 

 speaking students of this translation can scarcely be over-estimated. 



Mr. -). J. H. Teall has published, under the name of "British Petrog- 

 raphy," an admirable work, which, though treating only of British 

 eruptive rocks, is the most systematic and comprehensive work of its 

 kind that has yet been published in the English language. Irs size is 

 large octavo, with some 450 pages of text and 47 colored plates, show- 

 ing microscopic structure in l)oth ordinary and polarized light. The 

 work is not a mere popular compilation of old and well-known facts, but 

 is quite abreast of the times and thoroughly scientific, though at the 

 same time written in such style as to be intelligible to those who are 

 not experts in this particular branch of the subject. The American as 



