The temperature at sunset was 61°, and the evening clear. I obtained, with other observations, an immersion and emersion of the third satellite. Elevation 3,100 feet.
16th.--For several weeks the weather in the daytime has been very beautiful, clear, and warm; but the nights, in comparison, are very cold. During the night there was ice a quarter of an inch thick in the lodge; and at daylight the thermometer was at 16°, and the same at sunrise, the weather being calm and clear. The annual vegetation now is nearly gone, almost all the plants being out of bloom.
Last night two of our horses had run off again, which delayed us until noon, and we made to-day but a short journey of 13 miles, the road being very good, and encamped in a fine bottom of Powder river.
The thermometer at sunset was at 61°, with an easterly wind, and partially clear sky; and the day has been quite pleasant and warm, though more cloudy than yesterday; and the sun was frequently faint, but it grew finer and clearer towards evening.
17th.--Thermometer at sunrise 25°. The weather at daylight was fine, and the sky without a cloud; but these came up, or were formed by the sun, and at seven were thick over all the sky. Just now, this appears to be the regular course--clear and brilliant during the night, and cloudy during the day. There is snow yet visible in the neighboring mountains, which yesterday extended along our route to the left, in a lofty and dark-blue range, having much the appearance of the Wind River mountains. It is probable that they have received their name of the _Blue mountains_ from the dark-blue appearance given to them by the pines. We traveled this morning across the affluents to Powder river, the road being good, firm, and level, and the country became constantly more pleasant and interesting. The soil appeared to be very deep, and is black and extremely good, as well among the hollows of the hills on the elevated plats, as on the river bottoms, the vegetation being such as is usually found in good ground. The following analytical result shows the precise qualities of this soil, and will justify to science the character of fertility which the eye attributes to it:
Silica ----------------- 72.30 Alumina ---------------- 6.25 Carbonate of lime ------ 6.86 Carbonate of magnesia -- 4.62 Oxide of iron ---------- 1.20 Organic matter --------- 4.50 Water and loss --------- 4.27 ______ 100.00