76 The American Geolor/lst. February, 1895 
bled to sninniarize the main results ol" his labors in that region. 
Immediately connected with this work was the series of highly 
important investigations upon the volcanic rocks of the South 
Mountain, published in 1892 and 1898, which demonstrated 
the existence in that region of eruptives in all respects like 
those of recent origin. 
Another valuable series of papers embraces those which 
pertain to the petrograph}^, mineralogy and cr3^stallography 
of his native state, New York, the materials for which were 
largely gathered during the intervals of his academic work. 
We find fourteen of these extending over a period of six years 
(]88-l:-1890), among the more important of which are those 
relating to the petrography and contact-effects in professor 
Dana's "Cortlandt Series" on the lower Hudson ; and four 
papers on the serpentine dike at Syracuse, discovered by Van- 
uxem about ISiO, but lost sight of for nearly a half-century 
after. 
The vacation periods of 1884 and 1885 were spent in 
northern Michigan and the results of his work there were ex- 
pressed in an exhaustive treatise on the Greenstone-schist 
areas of the Menominee and Marquette regions, published as 
bulletin No. 62 of the United States Geological Survey (1890). 
Among his other special papers we find one bearing on the 
geology of the island of Fernando de Noronha, two on the 
rocks of the Sudbury District, Canada, one on rocks from 
Alaska and another on the crj^stallines of the Andes. 
At the close of the London meeting of the International 
Congress of Geologists, in 1888, professor Williams joined his 
instructor, Rosenbusch, in a visit to the crystalline regions of 
Norway, under the guidance of Dr. Hans Reusch, whose in- 
vestigations upon areal metamorphism have made those re- 
gions famous. Though he produced but a single brief paper 
upon the results of this trip, yet its efi'ects were undoubted!}'- 
far reaching u])on his subsequent work. 
In all these ])apers his writing is characterized by its lucid- 
ity and incisiveness, its freedom from contentiousness and its 
generous tolerance of adverse opinion. There was nothing- 
bellicose in his composition and he never penned a polemic. 
The value of his services to his science cannot be estimated 
alone from these technical papers in his special field of activ- 
