•ji The American Geologist. February. 1905 
spar than the "Laurentian" granite gneisses, in short that 
at the time of intrusion the Keewatin was nearer to melting 
than the "Laurentian" to consoUdating. I do not believe 
that these inferences are consistent with the theory that 
such granites are a softened formation immediately under- 
lying Huronian, Keewatin or Couchiching. I should rather 
expect that such softened sediments would cool wifh a 
coarseness of grain comparable to that of segregation veins 
and pegmatytes in so far as the same was not broken up by 
shearing and flowage. 
Whether I am right in this particular point, however, in 
general or not, and of course I can only speak with any 
degree of assurance for the few contacts I have personally 
examined, it seems to me that a careful study of the varia- 
tion of grain will assuredly throw light on this difficult 
problems as well as others. 
Lansing, /an.5, 1905. 
GERARD TROOST.* 
By L. C. Glenn, Nashville, Tenn. 
PORTRAIT-PLATE V. 
Gerard Troost, a pupil and friend of Hauy and Werner, 
one of the founders and the first president of the Academy 
of Natural Sciences of Philadelphia, professor of geology 
and chemistry in the University of Nashville, and first state 
geologist of Tennessee, was born at Bois-le-Duc, Holland, 
March 15, 1776, and died in Nashville, Tenn., /\ugust 14, 
1850. Though his parents had but limited means, he was 
educated at the University of Leyden, where he received 
the degree of Doctor of Medicine, and at the University of 
Amsterdam, where in 1801 he received the degree of master 
in pharmacy. Much of his time was devoted to chemistry 
and natural history and especially to the then infant sciences 
of geology and mineralogy. 
• The writer has drawn quite freely on Dr. Philip Lindsley's oration 
on the life and character of Dr. Troost. Acknowledgements for infor- 
mation and assistance in various ways are also gratefully made to Ex- 
Gov. James D. Porter, and Mr. Jno. M. Bass, president and secretary, 
respectively, of the University of Nashville; to Prof. Charles Schuchert 
now of Yale; to Mr. Chas. J. Fox of the Academy of Natural Sciences 
of Phila-delphia; to Mr. Lewis Stein of Spring Hill, Ala.; and to Dr. 
James M. Safford, of Dallas, Tex. 
