94 Henry Draper — Atmosphere of the Rocky Mountains. 



the sun sends down scorching rays all day long on the alkali 

 plains where only sage plants aie sparsely scattered and even 

 on horseback one can see the heated waves rising from the 

 ground. The air is far from being moist for the lips are apt to 

 crack and bleed, and the mucous membrane of the nose is 

 parched. "When the sun sets the ground radiates rapidly, and 

 we frequently had by morning one-quarter of an inch of ice in 

 our vessels of water standing outside the tents. These plateaus 

 are on an average about 7250 feet above the sea. The mere 

 fact of broken ground and wooded surroundings does not 

 however suffice to produce, even at this season, a tranquil ;iir. 

 for when we rode over the Rocky Mountains along the margin 

 of perpetual snow to the headwaters of Snake River, and 

 camped at Trout Lake nearly 10,000 feet high, though the air 

 was exceedingly transparent it was very unsteady. I rose at 

 four A. M. to see Yenus, and her splendor was so great that it 

 led to a most delusive estimate of her apparent size. Occa- 

 sionally during clear frosty weather in midwinter a night of 

 similar characteristics is seen at m}' observatory. On such an 

 occasion I obtained at the principal focus of the 15£-inch re- 

 flector a photograph of the Moon near her third quarter in less 

 than a second. 



The officers of Fort Steele and the guides say it would be im- 

 possible to do any astronomical work in this region from the 

 middle of October till the middle of May, that is, for seven 

 months. The fierce winds, heavy falls of snow and intense 

 cold would be unbearable. Even "in the beginning of Septem- 

 ber we needed large camp fires in the morning and evening. 

 Our camp at Trout Lake could only be reached for six weeks 

 in summer on account of the depth of snow in the fallen timber. 



On the whole it may be remarked of this mountain region 

 that the astronomical condition, particularly for phot 

 researches, is unpromising. In only one place were steadiness 

 and transparency combined, and only two nights out of 

 fifteen at the best season of the year were exceptionally 

 fine. The transparency was almost always much more 

 marked than at the sea level, but the tremulousness was as 

 great or even greater than near New York. It is certain that 

 during more than half the year no work of a delicate < iiunic- 

 ter could be done. At the end of August in sheltered 

 positions, and in good tents, we slept under half a dozen thick- 

 nesses of blanket and only partially undressed. Such a degree 

 of cold distracts the mind and numbs the body. Apparently* 

 therefore, judging from present information, it would not be 

 judicious to move a large telescope and physical observatory 

 into these mountains with the hope of doing continuous work 

 under the most favorable e' 



