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 

 Eed, 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. Fremont, as assistant, and Charles Geyer, 19 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 

 this point was not known; and my addressing myself to the reverend 

 fathers, the Jesuits, and engaging them in making meteorological 

 observations, was the first approach toward obtaining it. The late 

 Rev. Mr. Van Sweevelt charged himself with the task, receiving 19 

 months of observations, made 5 times a day, through the years 1835 

 and 1836. When Mr. Van Sweevelt was obliged to discontinue his 

 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 

 some time the members of the Western Academy have undertaken a 

 regular system of meteorological observations, we have reason to 



is Karl Andreas Geyer. Chronik des Gartenwesens. 3:185-187. 1853. 



Reich enbach, H. G. Karl Andreas Geyer. Kew Garden Misc. 7: 

 181-183. 1855. 



Spaulding, Perley. A biographical history of botany at St. Louis, 

 Missouri. Pop. Sci. Month. 1909: 124-125. 



