100 Trans. Acad. Sci. of St. Louis. 
scientific tour. His intention was to explore the Alle- 
ghany Mountains to the Southern States; to ascend the 
Red, the Arkansas and the Missouri rivers, and to ex- 
amine the Mississippi river from its mouth to its source. 
During the five years he was engaged in these excursions 
he made numerous observations, calculated to serve as 
the foundation for an astronomical and physical ge- 
ography of this country. In connection with this work 
he also studied the customs, habits, and languages of the 
several Indian nations that occupied the vast territory 
which he explored. 
The government arranged with Nicollet to extend his 
survey south and west of the country which he had al- 
ready explored. On this survey he was accompanied by 
John C. Frémont, as assistant, and Charles Geyer,’ a 
St. Louis botanist. 
While preparing for this expedition he was ably as- 
sisted by Dr. George Engelmann and the Jesuit Fathers 
of St. Louis University. He acknowledged this assist- 
ance in the following words: 
“All these altitudes, with the exception of what is south of the en- 
trance of the Ohio, have been referred to the ordinary low water in 
the Mississippi at St. Louis. The absolute height of the barometer at 
fathers, the Jesuits, and e in g meteorological 
observations, was the first teed meats obtaining it. e late 
Rev. Mr. Van search charged himself with the task, recei 9 
observations, I had the good fortune to find a successor, not less 
zealous, in Dr. Engelmann, who followed these observations with a 
regularity that was unlooked for from a person so occupied, other- 
wise with professional engagements. The years to which these obser- 
vations refer are 1837, 1838, 1839, and some months of 1840. As for 
e e members of the Western Academy have undertaken a 
regular system of meteorological observations, we have reason to 
19 Karl Andreas Geyer. Chronik des Gartenwesens. 3:185-187. ae 
Reichenbach, H. G. Karl Andreas Geyer. Kew Garden Misc. 
181-183. 1855. 
Spaulding, Perley. A biographical history of botany at St. Louis, 
Missouri. Pop. Sci. Month. 1909: 124-125. 
