NATURAL HISTORY REPORT ON WESTERN DIVISION. 
219 
on the north, up to the very shores of the sound, and on the south covering, in a similar manner, 
all the country limited on the west by a broken line drawn from the sound to a point on the 
Columbia a few miles below Cape Horn. The eastern range, as we have seen, throws out high 
spurs between the Yakima and its branches, covering all the country north of this river up to the 
Columbia. As there is another high range running northeast from the mouth of the Klikatat, and 
only terminating with the Columbia after coursing the Yakima, from six to ten miles to the south 
of it, we may safely infer that most of the country between it and the northern river-range of the 
Columbia is either mountainous or high, broken table-land. The country east of the Okinakane 
river, and north of the Columbia, having been found mountainous, the Columbia river may be 
taken generally as the eastern limit of the mountains, or of high mountainous country. The main 
range, and all the territory west of the range, are heavily timbered with pine, fir, larch and cedar. 
The eastern limit of timber is the Columbia river from Fort Okinakane to the mouth of the 
Wenatshapam, a right line from that point to the forks of the Sahpenis, and a right line thence 
to the Dalles of the Columbia. The soil throughout is uniformly light, shallow and sandy? 
and most of the country is sterile, barren and desolate, unfit for the purposes of agriculture, 
in its present state, and incapable of being reclaimed. The rivers are all mountainous in 
character ; currents rough and rapid, and beds stony. The variation of the needle is east. This 
variation decreases from the coast as you proceed eastward to the main Cascade range ; beyond 
which, in the same direction, it increases as you proceed. I am not aware that any exact ratio 
exists in this increase and decrease. The following examples will give some general idea of the 
state of increase and decrease: 
At Olympia, the variation is. 21° 
At Fort Vancouver, the variation is. 19° 45' 
At Chequoss, the variation is... 16° 5' 
At Ketetas, the variation is. 17° 34' 4 1" 
At Wenatshapam, the variation is. 18° 50' 27" 
And it similarly increases towards the east. The minimum is about 16°. 
I am, very respectfully, your obedient servant, 
J. K. DUNCAN, 
Second Lieutenant 3 d Artillery. 
Capt. George B. McClellan. 
9. Natural history report of dr. j. g. cooper, naturalist, of western division. 
General Notes on the Natural History. 
Sir: The country traversed by your division presents several well defined and very distinct 
zoological and botanical regions. 
The limited time of the survey, and the extent of country traversed, do not afford sufficient data 
for defining the limits of these regions and their peculiar products with accuracy, but I will 
attempt, in the following sketch, to give some idea of their outlines. 
It will be observed that there are two great regions very distinct and peculiar in their products, 
both animal and vegetable, that of the forests and that of the plains. The first of these is divisible 
into sub-regions—for example, the alpine summits of the mountains and the small prairies. The 
second also presents several sub-regions—for example, the rocky hills and the sandy valleys. 
The rivers and their immediate banks form a region which differs but little in products on either 
side of the Cascade mountains—all those met with being tributaries of the Columbia. All the 
above sub-regions differ more or less in the animals and plants peculiar to them, as may be 
seen from the collections made, and the notes in connexion with each of them. 
