xviii 
BOTA^TY. 
and on five days there was rain. On the 16th, snow fell on Star Peak. In 
October, twelve days are recorded as clear and no rain fell on the remainder. 
In November, six days only were clear and on five days rain, with snow upon 
the mountains on the 6th, and the unusual occurrence of frost on the 23d 
and 25th in the lower Humboldt Valley, though since early in October the 
minimum of the thermometer had often been below the freezing point. 
December was much more generally cloudy and with several heavy storms, a 
rain on the 8th continuing all day. On the 17th, a foot or more of snow fell, 
which drove the party in from the field, followed on the 23d by a very severe 
rainstorm that was repeated on the 30th and 31st. 
The winter of 1867-8 was spent at Carson City, at the base of the 
Sierras, in about latitude 39° 10' and at an elevation of 4,700 feet. Here a 
snow fell early iu January to the depth of about a foot, which remained until 
March, reenforced by occasional very fight snows, the outskirts of severer 
storms in the mountains above. Though more or less cloudy through March 
very little rain fell until the 1st of April, and warm spring-Hke weather 
began two weeks later. Flowers appeared at once and vegetation advanced 
rapidly, so that on the 8th of May the party again took the field, depending 
upon grass for the support of the animals. For six weeks later the weather 
was unsettled with occasional light snows and showers, two or three times 
continuing nearly all day. The last sfight snowfall was on the 24th of June, 
and summer immediately followed. 
In the three months from July to September, 1868, which were spent 
priiicii^ally iu the vicinity of the East Humboldt Mountains, there were 
eleven days in July and five days in early August upon which rain fell, mostly 
in severe thunder storms originating upon the peaks and passing eastward over 
the valleys. From that time until the 10th of October there was but a single 
light shower. 
The only basis upon which the mean annual temperature of this region 
can at present be calculated is found in the unpubfished observations made 
at the several military posts, under the direction of the Medical Department 
of the United States Army. These records for the years 1867 and 1868 
nuulc lit (Jamp Douglas near Salt Lake City, at an altitude of about 4,500 
feet, show a mean ttnnperature for the months of August, July, September, 
and June, (arrangiug the months in the order of their temperatures,) of 
70.8° F.; for October, May, April, and November, of 51.0° ; for December 
