23 2 THE POPULAR SCIENCE MONTHLY. 



either to New Brunswick or Nova Scotia, to continue his explorations, 

 in the course of which he would often lecture in the different towns to 

 obtain means of paying his field expenses. In 1864 Mr. Hartt was 

 employed, with Profs. Bailey and Matthews, on the geological survey 

 of New Brunswick, and, while engaged in this work, obtained the first 

 full proof of the existence of primordial strata in that province. Many 

 of his discoveries in Nova Scotia and New Brunswick were published 

 in the Provincial Government reports, and also in Dr. Dawson's "Aca- 

 dian Geology." Hartt's constitution, though well able to withstand 

 the severest kind of fatigue in exploration, was not proof against the 

 damp, chilly atmosphere of his native land, and from this cause he often 

 suffered much ; so it was probably fortunate for him that just about 

 this time his attention was attracted toward a new field. 



Upon the organization of the Thayer Expedition to Brazil, by Prof. 

 Agassiz in 1865, he was appointed one of its geologists, and henceforth 

 to the time of his death he was ever a most devoted investigator of 

 South American natural history. As a member of Prof. Agassiz's 

 party he explored the neighborhood of the coast from Rio de Janeiro 

 to Bahia, and ascended many of the rivers, making large zoological 

 collections, but finding little of interest in the geology. Aided by New 

 York friends he returned to Brazil alone in 1867, this time examining 

 with the greatest care the reefs of the Abrolhos Islands, and those 

 of the coast, as well as the geology of a part of Bahia and Sergipe. 

 With the material thus far collected he began the work of writing up 

 his geological reports in the capacity of geologist to the Thayer Ex- 

 pedition. This report was to have been included along with those of his 

 chief, but under Hartt's hands it grew to such size that it was pub- 

 lished separately in 1870 as the "Geology and Physical Geography of 

 Brazil." In addition to the account of Hartt's researches, it included 

 the best results of all who had ever published on the geology of the 

 country. 



After his return from the Thayer Expedition, the time he spent in 

 this country until 1868 was devoted mostly to scientific teaching and 

 lecturing in and around New York City, where he attained much suc- 

 cess and made many warm friends. Early in 1868 he was elected 

 Professor of Natural History in Vassar College, a position he resigned 

 in the fall of the same year, to accept the chair of Geology in Cornell 

 University. Shortly after assuming his duties at Cornell, he was mar- 

 ried to Miss Lucy Lynde, of Buffalo, New York, who is now left with 

 two children. In 1869 he was made General Secretary of the American 

 Association for the Advancement of Science, to serve at the meeting 

 of 1870 ; but a third expedition to Brazil, which he had been planning, 

 called him away before the Association met. This trip was made in 

 company with Prof. Prentice and eleven students of Cornell Univer- 

 sity, and was the largest of his own organizations from the United 

 States. With this party he entered what was really a new region for 



