IV INTRODUCTION. 



Doctor George G. Shumard, of Fort Smith, Arkansas, who 

 faithfully discharged the duties of surgeon to the command, 

 also made important contributions to the department of natu- 

 ral science, by collections of specimens of the rocks, minerals, 

 soils, fossils, shells, and plants, of the different localities which 

 we traversed; and of these, the plants were placed in the 

 hands of Dr. John Torrey, of New York, the eminent botanist 

 so well known to the army by his able reports on the collec- 

 tions of Fremont, Emory, and others. 



The shells were intrusted to Professor C. B. Adams, of 

 Amherst. His report, as presented, possesses a melancholy 

 interest, as being almost the last scientific effort of this distin- 

 guished conchologist, whose loss science has so recently been 

 called upon to deplore. 



The specimens of rocks and minerals have been examined 

 by President Hitchcock, of Amherst College, with important 

 results, while copious remarks on the general geology of the 

 country have been supplied by Dr. Shumard, who has also 

 furnished some notes on the conchology of the route. 



The minerals and soils have been analyzed by Professor 

 C. U. Shepard, who detected among them a new species. 

 Finally, in the hands of Dr. Benjamin F. Shumard, the fossils 

 have yielded several novelties to science. All these reports 

 upon the natural history of the expedition will be found de- 

 tailed at length in the appendix. 



The barometrical observations which are given were taken 

 from both forms of the instruments, and exhibited a remarka- 

 ble agreement until the 8th of June, when we had the mis- 

 fortune to break the mountain barometer, and were obliged 

 subsequently to depend solely upon the aneroid. This I be- 

 lieve to be very reliable, as it has been tested since our return 

 by a careful comparison with several other instruments in 

 possession of Benjamin Pike & Son, New York, and found to 

 be in perfect order. 



In order to obtain as intimate a knowledge as possible of 

 the country over which we passed, I was necessarily absent 

 from the train a great portion of the time while it was in mo- 

 tion ; and during such periods the command devolved upon 



