MOUNT RAINIER 



atmospheric conditions prevailing in the immediate 

 region of the mountain. More specifically, the pro- 

 cess consisted in determining the atmospheric pressure 

 and temperature at an imaginary sea level vertically 

 under the mountain, which level I shall subsequently 

 call the "mean base." 



In this I was greatly assisted by a careful study of 

 the daily weather charts issued by the government, 

 Mr. Pague having kindly loaned me his official file for 

 July. I thus practically had at my disposal observa- 

 tions from all the important points on the Coast, both 

 before and after the principal observation. With due 

 regard to the position and direction of the isobars, 

 and giving proper weight to the observations at each 

 of the four base stations, I finally deduced 30.130 inches 

 as the value of the pressure at the mean base which 

 best satisfied all the data. It ought to be said, perhaps, 

 that this result does not depend upon my judgment to 

 any appreciable extent, but was legitimately worked 

 out from the observations and isobaric lines. 



In determining the mean temperature of the air 

 column extending from the mean base to the summit 

 of the mountain, the observations made by Professor 

 McClure during the previous week in the vicinity were 

 so numerous and well timed as to leave far less than 

 the usual amount of uncertainty. Making due allow- 

 ance for the moderate elevations of the stations, these 

 observations show clearly that the temperature about 

 the mountain at that time followed that of Seattle 

 very closely, and was also not much different from that 

 of Portland, but departed notably from both the heat 

 of Walla Walla and the low temperature of Fort 

 Canby. Allowing proper weight to these facts, the 

 observations at the base stations, with that of Professor 

 McClure at the summit, gave 49 degrees Fahrenheit 

 as the mean temperature of the air column. 



I regard the method of reduction outlined above as 

 possessing decided advantages over any other that 



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