H. Ganneti—The “Timber Tine.” O77 
Thus it is seen that in the same latitude, there is a very 
marked difference in the height of the timber line. The less 
the elevation of the surrounding country, other things being 
equal, the lower is the limit of timber. 
his suggests a farther point. The upper limit of timber 
must have. approximately the same mean annual temperature 
everywhere. Of course it will differ to a slight extent in dif- 
general principle. The determination of this rig sated accu- 
rately is, without direct observation, of course, impossi 
ave, however, computed it approximately from such dats as 
are available, and have found tolerably close accordance among 
the resulis. 
mean annual temperature decreases ae 1° Fah. for 
each 300 feet of abrupt ascent. In the case of Pike’s Peak 
and Colorado Springs, where the difference of elevation 3 is more 
than 8,000 feet, the change is 1° for each 295 feet. In the case 
of Mt. Washington and Shelburne, New Hampshire, it is 325 
feet for each degree. The former case is the most favorable in 
every respect, and as most of our results are drawn from the 
western region, I have adopted, as a round number, 300 feet. 
ow, if the average mean annual temperature all around the 
base of a mountain were known, it would be a very simple 
Matter to determine, with some accuracy, the temperature at 
timber line, knowing its height and the mean height of its 
base. The nearest approach witee can be made to this, is to 
no means correct. Using, howev the manner indicated, 
such data as are at hand, I have obuined the following yest 
? | BASE STATION. Tem- 
Height ¥ 
Mountains, ete of tim- | Hei nt | Mean thre at 
ie bar sage Name. infect. an. tem. | timber 
: line. 
Cun: ningham Pass, Colo.) 11 ,500 Fort Garland, 7,945 |" 43° 31° 
Mt. Lincoln, Colo. 12,051, Fairplay, sf 9,866 | =. 36° 31° 
Mt. Sivericls, Colo., 11,5 49 9,965 38° Sn” 
t. Guyot, Colo., 1, tH 9,965, 38° 32° 
Mt. Powell, Colo., 1,600 ‘White River Agency, | 6,491 45° 28° 
Pike’s Peak, Colo., 1720 Goh lorado Springs, 6,032] 48° 29° 
Gray’s Peak, Colo., 244 48° 29° 
Wahsatch Mts., Utah, | 1¢ “600 lgaie tae City, 4,350} 52° 33° 
Mt. Washington, N. H., | 4.150 Shelburne, N. H.. 700| 42° 30° 
Mt. Marcy, N. Y., 4,851)Some ee 412 45° 30 
. | 4,851|Plattsburgh, N. Y., 18 44 29° 
Mt. Blackmore, Mont., | 9,550 0\Fo rt Ellis, Mont., 4,935| 44° 29° 
Mt. Doe Pe 9,002! 4,935 44° 31° 
Mt. Delano | g7s4| & Kw 4,935| 44° 31° 
