236, 



GEOLOGICAL SURVEY OF THE TERRITORIES. 



fall for the year aucl months. Yet even these are of great interest, as 

 they famish cumulative evidence in support of the opinion already ad- 

 vanced respecting the climate of Salt Lake Valley as compared with the 

 elevated regions lying east of it. 



The following extracts from the registers of Camp Douglass, near Salt 

 Lake City, and Fort Bridger, for the year 1870, will serve as a basis of 

 comparison : 



These two stations, by air-line, are not exceeding one hundred miles 

 apart, the latter being about half a degree north of the former, and 

 over 2,000 feet higher. 



An examination of these tables shows a constant dilference that is 

 somewhat remarkable; the monthly means, maxima, and minima, with 

 the single exception of one maximum, (where the two are the same,) 

 of Camp Douglass being higher than those of Fort Bridger. The 

 dilference betvt^een the monthly means is never less than 4°.5, and never 

 more than 13o.7, the average for the year being 9°.46, A comparison 

 of the extremes shows a greater difference, but this probably arises in 

 part from the different methods by which they were obtained, those of 

 Camp Douglass being only the extremes at the times of observation, 

 ■while those of Fort Bridger were obtained by a maximum and minimum 

 instrument. Yet even these columns indicate a corresponding differ- 

 ence, that between the maxima varying from to 19, averaging for the 

 year 9.92, or less than a half-degree more than the average difference for 

 the year between the monthly means. The minima cannot properly be 

 compared, as those of Camp Douglass do not give the extreme cold of 

 the night, or intermediate hours between observations, while those of 

 Fort Bridger do. 



A comparison of the seasons is quite interesting. To show this at a 

 glance, I append the following table, with a column of differences: 



