764 THE JOURNAL OF GEOLOGY. 



the latter period of his career broadly geological. And while, 

 by reason of the greater demands on his time of university duties, 

 his earlier investigations lacked comprehensiveness, yet his treat- 

 ment of whatever material was at hand was thorough and system- 

 atic, and his methods of presentation are models of logical 

 arrangement and concise statement. Even his more fragmentary 

 researches often contributed to the elucidation of principles of 

 fundamental importance and of general application. Thus his 

 study of some remarkable pyroxenes led him to the demonstra- 

 tion of the possibility of hemihedrism in the monoclinic crystal 

 system ; while his study of certain hornblende and its gliding 

 planes contributed in no small degree to the proper crystallo- 

 graphic orientation of this mineral with reference to pyroxene. 



In the realm of petrography he improved every opportunity, 

 whether small or great, to advance the boundary and efficiency 

 of this o-rowinor science. The accidental notice of an obscure 



o o 



body of serpentine in Syracuse, N. Y., long since buried by town 

 improvements, and its investigation by modern microscopical 

 methods, led to the complete refutation of the elaborate theory 

 of Dr. T. Sterry Hunt, so far as it related to the chemico- 

 sedimentary origin of this once well-known occurrence of serpen- 

 tine. The identification of a glass-breccia, now metamorphosed, 

 in the pre-Cambrian crystalline rocks of the Sudbury district, 

 Canada, demonstrated the existence in this region at that 

 geologically early date of volcanic action, whose products 

 differed in no appreciable manner from those of modern vol- 

 canoes. 



Soon after his establishment in Baltimore he began the study 

 of the rocks of the neighborhood, selecting from among the 

 crystalline schists those most closely allied to massive igneous 

 bodies, and examining their transitions into more and more 

 metamorphosed forms. In thus early attacking the problem of 

 metamorphism he showed the influence of his environment, which 

 received a powerful impetus from the work of Johannes Lehmann, 

 published the year following, in 1884. This he eagerly assimi- 

 lated, and, appreciating its great value, brought it to the notice 



