64 MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 



Mont-Blanc (15,780 feet), and tlie railroad which ascends from Manitou is a great 

 convenience. For such observations as require a blue sky rather than good 

 seeing, Pike's Peak (when not surrounded by forest-fires) would seem to offer 

 some important practical advantages over other mountains of equal altitude. 

 But if good seeing is essential the peak is not to be recommended. 



Mountain-Sickness on Pike's Peak. 



Professor Hale, 1893, reports that " about two-thirds of the tourists 

 who came up tlie mountain on the train each morning were affected by 

 the altitude,* and during our stay we saw one or two very serious cases 

 of mountain-sickness. While not much troubled, Professor Keeler 

 and I found prolonged hard work very fatiguing, and any slight extra 

 exertion at once increased the action of the heart" 



Mrs. Hale was unable to remain on the summit, although she, natu- 

 rally, was not called on for any extra exertion there. 



Most mountains are (for obvious reasons) quite cloudy (Pike's Peak, 

 Mont-Blanc, etc., as examples). The great advantage of the mountains 

 of California, Arizona, New Mexico, and Southern Colorado is their 

 remarkable freedom from clouds. I have not been able to see any re- 

 port of the conditions on the mountains of Algeria, but one would 

 think, a priori, that they should be excellent. 



Lowell Observatory, Flagstaff, Arizona (7300 feet). 



In the American Meteorological Journal for March, 1895, Mr. A. E. 

 Douglass, one of the staff of the observatory, gives a table with 

 numerical estimate of the quality of the seeing (its steadiness) from 

 September 28 to December 31, 1894, while he was conducting certain 

 very interesting experiments on air currents within the tubes of large 

 telescopes. These experiments were usually made only when the see- 

 ing had become too poor for other observations. The seeing (steadi- 

 ness) is marked in eleven grades ; the best is 10, the worst is 0. It is. 

 noteworthy that the seeing was worse than 6 on some part of 48 nights 

 out of 51 nights recorded. f 



The conditions at Flagstaff are, then, very different from those at 

 Mount Hamilton (or Mount Wilson) where the whole night is apt to- 

 be good if any part of it is so. At Flagstaff it appears that a portion 

 of nearly every night is unsatisfactory, and Mr. Douglass says that, 

 almost the entire month of December was so.:}: 



* The train takes 1 hour 45 minutes to rise from the station at Manitou (6563 

 feet) to the summit station (14,115 feet). The time required for the journey down 

 is 1 hour 15 minutes. The maximum speed is 8 miles, the minimum, 3 miles per 

 hour. 



1 1 have not counted the estimates for November 2, 3, 4, 5, and 9, where two esti- 

 mates are given, one greater and the other less than 6. 



X In this connection, see a letter by Professor W. H, Pickering in the section 

 of this volume devoted to the Arequipa Observatory, page 40. 



