METEOROLOGY. 317 
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Means for 1853-254-255. | 3 E й 3 к В нам 
КОЖ ee ee we Sa. F " 
E! 8 = A 3 5 
3 4 < 2 E - 2 м 
EA Feet. е . 
Cantonment Stevens...... "OT | 46 20 | 113 55 | 3,419 | 48,0 69.6 45.6 94.9 47.0 | 1853-54 е ж” 
Fort Оеп... 46 35 | 113 55 | 3,984 ا‎ a 1854—55 | ———— 
Fort Hall ‚| 4304| 112 97 | 4,500 47.4 | 93.6 |........| Winter, 1849-50. 
Salt Lake City 40 46 | 112-06 | 4,351 | 51.7 15.9.]. esu 958 ДИ УРРА Winter, two years, 29° ‚1, 
There seem to be no data to warrant the extension of summer temperature of 70° much north 
of the Missouri river, as has been done by Mr. Blodgett in his last work, and it is accordingly 
made to run near the cóteau north of that river, which rises several hundred feet above it, 
forming the ridge between it and the Saskatchawan. On the other hand, west of the mountains, 
the line of 70° is substituted for 65? for Bitter Root valley, the prairies near Flathead lake, 
and thence down the valley of Clark's Fork and the Columbia, from Fort Colville south. The 
rapidly decreasing altitude compensates for the greater distance north of part of this tract; but 
allowance should be made, in some places, for the local influence of surrounding mountains and 
forests. 
The whole of the Great Plain, and the unwooded hills and valleys north and west of the 
Great Bend of the Columbia, are assumed to have a mean summer temperature above 70°, 
which is partly proved by a comparison of temperatures on the same days at. Fort Dalles and 
in the Yakima valley. 
A series of observations at Fort Walla-Walla, twenty-nine and a half miles east of the 
Columbia, at the confluence of the Walla-Walla with that river, altitude 1,396 feet, shows that 
the lowest parts of-^iz-—7!ain have a summer temperature as high as 73°, and a line has been 
drawn to approxilllately include this district. 
The following are the means of observation at this post, (uncorrected :) 
Fort Walla- Wala, 1851— 58.—Summer, 739.1; winter, 34*.1; autumn, 529,6; spring, 519.8. 
The winter, compared with the mean for four winters at Lapwai, on the Kootkooskus, and five 
at Fort Dalles, appears a little below the average for the latitude and elevation. agn 
From the two former records the mean for the Great Plain is assumed as above 35? in winter, 
though records at Fort Colville are wanting to complete the curve, and the northern parts of 
the region included may be a little colder. ; 
259 is retained as the mean for the Bitter Root valley, although the second winter's observe 
raises it to 27°.6. The lines of 65°, 60°, and 20° are approximately 
tions, as already shown 1 3 
; : each 1,0C0 feet, at points whose elevation is known, and then 
located, by allowing 3? for 
connecting them. 
There is too little known of the geography of 
known points in Washington Territory and Utah. 
No records for any point, except the Dalles, 
projected in the interior of Oregon, and too few 
mation by reduction from better known regions. 
West the Cascades and Sierra Nevada the lines are drawn from the same data recorded in 
Mr. Blodgett's book, but altered to conform more closely to the surface of the country. bw 
fixed points at which they were taken being usually in valleys, or on the low land Aes = 
coast, with high mountain ranges intervening, the lines are made to include only so mu 
Oregon to make a safe connexion between the 
exist from which the summer lines can be 
altitudes are known to make even ап арргохі- 
