PETROGRAPHY FOR 1887 AXD 1888. 



By George P. Merrill, Curator in the Xational Musemn. 



The years 1887 aDcl 1888, covered by this report, have been years of 

 unprecedeuted activity and progress in that branch of geological 

 science to which the name petrography is now commonly applied. 

 Accessions to the ranks of workers, both in America and abroad, have 

 been rapid and constant, and the science now holds a place in the 

 curricula of our leading institutions of learning.* Prior to 1880, al- 

 though beginniugs had been made by Wadsworth at Harvard, Hawes 

 at Yale, and Julien at Cokimbia College, yet the science was still prac- 

 tically unrecognized and almost unheard of in the majority of American 

 colleges and universities. At the present date it however holds a 

 lecoguized place in the curricula of Colby, at Waterville, Maine; Har- 

 vard and Amherst, Massachusetts ; New Haven, Connecticut ; Cornell 

 and Columbia, !New York ; Johns Hopkins, at Baltimore, Maryland ; 

 State University, at Minneapolis, Minnesota; State Mining School, at 

 Houghton, Michigan; State University, at Madisou, Wisconsin; and 

 in the University of California, at Berkeley, in that State. At many 

 other institutions, the subject is referred to incidentally in the regular 

 courses of geology and mineralogy, or is taken up to some extent by 

 post-graduate students working for the higher degrees. 



A pleasing and encouraging feature of this stage of work is the free- 

 dom from prejudice and preconceptions manifested by most classes of 

 students, and it is doubtful if any branch of science has shown a more 

 hopeful and healthful condition of affairs than that existing to-day 

 among petrographers. The disposition or desire at first manifest to 

 claim for the new departure all manner of possibilities, to solve im- 

 mediately the problems of rock classification, formation, durability, 

 and alteration, has already given way to a broader, more i)liilosophic 

 spirit; and petrographers in general are disi)0sed to hold opinions and 

 convictions in abeyance, to regard each new discovery in but the light 

 of one new fact from among the ciiaos of which, when sutfu^ient may 

 have accumulated, may be picked out the general principles governing 

 rock history and the history of the globe. 



* For a very complete account of mothod8 aud aims of petrography, tlie American 

 reader is referred to tlu^ neat little pamphlet of :W pages, l>y Dr. George II. Williams, 



entitled Modern Petrography, D. C. Heath &. Co., Boston. 



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