MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 59 



was close to the upper one, and in full view from it. Much of the 

 work was done at a third station, " Mountain-camp " (12,000 feet). 

 No point east of the Sierras possesses equal advantages for the 

 particular (solar) work referred to. The high peaks in the Rockj 

 Mountains, while admirable as meteorological stations, and compara- 

 tively very accessible (Gray's Peak, Pike's Peak, Mt. Lincoln, and 

 many others), are much affected by mist and cloud. Many stations in 

 the Sierras and in other ranges in California and neighboring States are 

 entirely suitable, but as Mount Whitney was the highest and most 

 southerly of the great peaks it was chosen. 



On the recommendation of Dr. Langley, seconded by a Committee 

 of the National Academy of Sciences, the Congress of the United 

 States has reserved from sale a considerable area, includino; the summit 

 and surroundings of Mt. Whitney, so that this station will be forever 

 available for the study of physical problems. A railway passes near 

 the foot of the mountain, and a comparatively small expenditure would 

 open practicable trails for baggage animals to the Mountain-Camp 

 above mentioned. During summer there is comparatively little snow 

 even at the highest part of the mountain mass. 



Mt. Whitney has, thus, many advantages as a high-level station for 

 meteorological and special astrophysical researches. It should be borne 

 in mind that its summit is but 880 feet lower than Mt. Blanc ; and 

 especially that it is very easy of ascent as far as 12,000 feet. The 

 summit itself, some 8000 feet higher, can be reached in about three 

 hours from the mountain-camp. 



From Dr. Langley 's notes I extract a few sentences bearing on the 

 astronomical conditions on Mt Whitney : 



August 16. The sky to-day, as always, is of the most deep violet-blue, such 

 as we never, under any circumstances, see at the sea-level. It is absolutely cloud- 

 less, and there is only a slight orange tint about the horizon at sunset. Carrying 

 a screen in the hand between the eye and the sun, till the eye is shaded from the 

 direct rays, it can f oUow this blue up to the edge of the solar disc without finding 

 any loss of this deep violet or any milkiness of the sky as we approach the limb. 

 It is an incomparably beautiful sky for the observer's purposes, such as I have not 

 seen equalled in the Rocky Mountains, in Egypt, or on Mt. Etna. 



It is perfectly safe to add to Dr. Langley's enthusiastic testimony 

 that there are literally hundreds of stations in California and the neigh- 

 boring States of equal altitude with his mountain-camp (12,000 feet) 

 where equally satisfactory observing conditions prevail, so far as 

 transparency is concerned. 



Dr. Langley's remarks above relate principally to the clearness of 

 the sky. Its steadiness^ as judged by the absence of twinkling of the 



