390 



Observations on the Physical Geography 



character of the climate both north and south. These mists 

 keep the country moist and sustain many small streams. There 

 is then no mystery in the prevalence of forests about the hills, 

 plains and mountains of the coast. ■ 



Again, the temperature of the coast and that of the interior 

 portions of the Western Section (west of the Cascade Range) are 

 widely different. In the Willammet, the summers are hot as well 

 as dry, the temperature usually varying between 68° and 90°.* 

 On the Sacramento the heat is much more excessive, — there is a 

 beautiful clear sky, but a parched land beneath ; and the long suc- 

 cession of hot days, the thermometer often up to 100° F., make 

 it a debilitating climate for a long residence, although excellent 



in other respects, excepting for a time in autumn when there are 



intermittent fevers. The rains do not set in till November or 

 December. 



On the coast at the mouth of the Columbia, the nights are 

 cold, and the days are hardly comfortable in summer without a 

 fire. At San Francisco, which is near the coast, the thermome- 

 ter in summer according to Mr. Lyman's observations in August, 

 1848, was not above 68° F. ; and chilly fogs were frequent, so 

 that fires were necessary to comfort.f A degree and a quarter 

 farther south, at Monterey, according to observations in 1845 by 

 Mr. Talbot H. Greene, the thermometer was not above 74° in any 

 part of summer ; in August, it ranged between 42° and 73°. 



Between the two extremes, the cold shores of Francisco and 

 the hot interior plains, lies the fertile valley of St. Joseph, forty 

 miles from the ocean, and separated from the valley of the 

 Joaquin by a ridge two to five thousand feet high. Here the 



airs are mild and pleasant throughout the season 

 chilling mists of the coast nor the parching heat 



neither the 



*Tho following facts are derived from tables by John Ball, made in 1832 and 

 18 :, at Vancouver, Oregon. (This Journal, xxvin, 9, 1835.) The hours of the ob- 

 servations are not given. 





T 



emp 



U 



u 



u 

 u 



u 



of December, 1832, 



January, 1833, . 



February, 



March, 



April, 



May, . 



June, 



July, . 

 August. . 



September, 



Extremes at 



morning. 



Extremes at 

 noon. 



82 and 53° F. 

 17 and 54 F. 



32 and 47 F. 

 12 and 40 

 3 J and 41 

 32 and 60 



45 ;md 60 

 11 and 50 



46 and 63 

 43 and 60 



40 and 54 

 28 and 58 



44 and 55 

 50 and 6<> 



45 and 6 

 50 and 75 



5 and 95 



7:i and <>:> 

 69 and 93 

 57 and 88 



Mean at noon 

 45 



48£ 



* ■ 



• » 



• • 



• • • 



84 h 



17 



11 



The observations made under the direction of Caj Wilk , #; e for July, the 

 *an at 2 P. ML 87 , for August 86°, for September 78°. (Xarrativ,-. v, 138.) 

 A full Report of the Meteorological observations of the Exploring Expedition, in- 

 iding those made in Ore n wad California vet to be published by Capt. Wilkes. 



! 





