2 BoJa7id Due)- Iriihg—ChamherJin. 
in En^laml, the impress of which in certain choices of language 
and methods of thought remained with him throughout his life. 
On his return he was able to resume studies, though it was neces- 
sar}' that the greater part of the texts should be read to him. This 
probably strengthened a memory naturally retentive and drove 
him to meditative and independent thought, since he was 
measurably cut ofE from indulgence in simple acquisition. A 
full course in the School of Mines, of Columbia College, gave 
him the technical foundation for his future work . 
During two of his summer vacations he found employment 
and practical experience in the coal mines of Wiconisco, Penn- 
sylvania. Soon after graduation he was appointed superinten- 
dent of the smelting works at Greenville, New Jersey. Follow- 
ing this he was employed during parts of two years upon the 
Ohio geological survey. His career Ihus far had lain chiefly in 
the line of technical work. From this he was turned aside in 
1870 by a call to the department of geology, mineralogy and 
metallurgy in the University of Wisconsin, and from that time 
onward his activities took two parallel lines, instruction and 
investigation. As an instructor his work was characterized by 
thoroughness, by a masterly command of the subjects he taught, 
b}'^ clearness of presentation and a graphic and humorous ex- 
position, by perfect caudor and sincerity, by earnestness, devo- 
tion and indefatigable industry — a rare combination of qualities, 
which made him not only a singularly effective instructor, but 
a worthy leader in all those moral and manly influences which 
characterize the true teacher. 
Professor Irving's first independent geological investigatiou 
consisted of the demonstration that the Baraboo quartzites of 
central Wisconsin are very much older than the adjacent upper 
Cambrian sandstone (Dikelocephalus horizon,) which was at 
the time a battled question.* Shortly after he made similar in- 
vestigations on the quartzites near Waterloo, Dodge Co., Wis.f 
Upon the inauguration of the recent geological survey of Wis- 
consin, (1873,) professor Irving was appointed one of the three 
*Onthe Age of the Quartzites, Schists aad Coaglomerates of Sauk Co., 
Wis. Am. Jour. Sci., vol. in, Art. xv, p. 93. The same in Trans, of Wis. 
Acad, of Sci. Arts and Letters, vol. ii, pp. 107-119. 
fNote on the Age of the Metamorphic Rocks of Portland, D.)dge Co., 
Wis. Am. Jour. Sci., Vol. v, Art. xxxi, p. 282. 
