Xviii BOTANT. 



and on five days there was rain. On the 16th, snow fisll 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 26th 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 in January to the depth of about a foot, which remained until 

 March, reenforced by occasional very light 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-like 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 slight snowfall was on the 24th of June, 

 and summer immediately followed. 



In the three months from July to September, 1868, which were spent 

 principally in 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 can at present be calculated is found in the unpublished observations made 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 

 made at Camp Douglas near Salt Lake City, at an altitude of about 4,500 

 feet, show a mean temperature for the months of August, July, September, 

 and June, (arranging the months in the order of their temperatures,) of 

 70.8° F.; for October, May, April, and November, of 51.0° ; for December 



