22 MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 



vol. CXI (1890). The following is a brief absti-act. The object of the expedition 

 M^as to determine whether oxygen exists in the solar atmosphere. When the 

 solar spectrum is examined with a spectroscope, at sea-level, some lines are seen 

 which may be due to oxj'gen in the sun's atmosphere, or which may be due to 

 absorption effects in our own terrestrial air. If the spectrum is examined from 

 terrestrial stations of great elevation, the absorptive effect of the earth's atmos- 

 phere is less and less, as the station chosen is higlier and liigher, naturally. In 

 October, 1888, M. Janssen made the ascent of Mt. Blanc as far as the Orands- 

 Mulets (about 9800 feet above the sea), and obtained satisfactory observations ; in 

 1890 he ascended to the very summit of the mountain (15,780) feet, and repeated 

 his work. The immediate scientific result of his two expeditions is that oxygen 

 is not present in the gaseous envelopes which surround the sun ; or, at least, if 

 ox3'gen is present, it is in a condition entirely different from that known to us 

 in our laboratories, and does not produce that absorption of light which is marked 

 by the system of lines and bands familiar to spectroscopists. 



This is a scientific conclusion of capital importance in questions of solar physics. 

 It has been confirmed by later observations by the same observer on the summit 

 of Mt. Blanc (1895). 



The expedition of M. Janssen has an interest quite apart from its purely astro- 

 nomical one. In fact M. Janssen lays the chief stress, in the paper cited, upon 

 the question of the establishment of a high-level observatory at the top of the 

 mountain, and points out the great scientific advantages to be gained from such 

 an observatory devoted to questions of terrestrial as well as of solar physics. If 

 such an observatory is to be founded anywhere it is tolerably certain that sta- 

 tions can be found which are far more favorable than Mt. Blanc. Pike's Peak, 

 for example, is 14,134 feet high, and the summit can now be reached by a railway. 

 There is no reason why a station on Pike's Peak could not be maintained through- 

 out the year, since the U. S. Signal Service kept its observers there for several 

 years continuously. There are also many stations in the Sierra Nevada of Cali- 

 fornia which have natural advantages far above those of Pike's Peak. It would 

 seem, then, that for scientific purposes alone, it might be better to maintain a 

 station at one of these places (to speak only of mountains in North America), 

 than to attempt to found such a station on the summit of Mt. Blanc, which can 

 be reached only with great difficulty and some danger under the most favorable 

 conditions, and which is practically inaccessible during many months of the year. 



The chief interest in M. Janssen's paper, after its astronomical importance, is, 

 for VIS, the exhibition of his intrepidity in planning such an ascent at all, and of 

 his cool daring in accomplishing it. M. Janssen is sixty-six years of age, and 

 suffers from a severe lameness, so that it is practically" impossible for him to make 

 continued exertion in walking. During his ascent to the Grands-Mulets in 1888 

 it was with the greatest difficulty and danger that he attained the cabin at that 

 point, although the ascent is by no means difficult for good walkers. Many 

 ladies, for example, go as far as this. How then was it possible for him to reach 

 the summit, 6000 feet higher, which lies beyond a wilderness of huge rocks and 

 great glaciers with their crevasses, and the route to which runs along steep aretes 

 only two or three feet wide, with terrific slopes on both sides of the narrow 

 crests? To appreciate the sj^lendid daring of M. Janssen, it is necessary to read 

 his own words. It is only possible hei'e to give the merest summary of them. 



Before leaving Meudon, M. Janssen had a sled constructed which resembled in 

 general pattern the reindeer sledge of the Laplanders. In front and behind this 

 were double parallel cords, united by wooden rungs like ladders. A long line was 

 attached to the front of the sled, and another to the rear. The ascent was made 

 as follows : M. Janssen was seated in the sled, and twelve selected guides managed 

 its movements. Two guides, far in advance, sunk an ice-axe in the snow as far 



