MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 21 



ascents have been made, but none of them without difficulty and dan- 

 ger. A glance at the accompanying illustrations is instructive. 



Mountain-sickness has been ex]3erienced on Mont Blanc l3y the 

 great majority of climbers from the time of De Saussure until now. 

 De Saussure found his powers of work much diminished. His words 

 are: " Je ne pus faire dans ces qua-tre heures et demie toutes les expe- 

 riences que j'ai frequemment achev^es en moins de trois heures au 

 bord de la mer." Here we have something like a numerical estimate 

 of the loss of physical vigor. 



Such questions will soon receive a definite solution from the exj^e- 

 riences of observers in actual residence on the summit. 



The establishment of a meteorological observatory on the Pic-du- 

 Midi and of stations at the Theodule pass (3300 metres) and on the 

 Sonnblick (3100 metres), of late years, suggested to Monsieur J. Vallot 

 of the French Alpine Club, that a station on Mont Blanc might be 

 practicable and useful. In 1887 a party of thirty guides transported 

 to the summit a tent and sufficient material to allow M. Vallot and three 

 other persons to remain three days. 



M. Vallot recognized the great difficulties to be overcome in estab- 

 lishing a station at the very summit, and therefore determined to erect 

 a permanent meteorological station at the Eochers des Bosses (4365 

 metres, 14,321 feet). 



It is M. Vallot's opinion that this station is preferable for meteoro- 

 logical purposes to one at the summit; and it is certainly far more 

 accessible. M. Vallot's observatory was erected in 1890. In the same 

 year, M. Janssen proposed to build an observatory at the very summit, 

 and as a preliminary step did erect an observatory station at the 

 Grands-Mulets (3000 metres, 9843 feet). The observatory of M. 

 Vallot was erected at his own expense. The various stations con- 

 structed under the direction of M. Janssen have been built from a 

 fund provided by subscription, and are, I believe, annexes of the 

 Government Physical Observatory of Meudon, near Paris. Both 

 these establishments pursue the most liberal policy towards scientific 

 observers, and open their doors to any investigator ; in fact, even to 

 tourists and mountain climbers. M. Janssen's observations on the 

 presence of oxygen in the atmosphere in 1891 were made from M. 

 Vallot's observatory, and M. Janssen's establishment on the summit 

 is to be international in character. This is certainly as it should be. 



M. Janssen's Expedition to the Summit of Mont Blanc (1890).* 



The original account of M. Janssen's scientific expedition to the summit of 

 Mont Blanc is printed in the Comptes Rendus of the Paris Academy of Sciences, 



* From the Publications of the Astronomical Society of the Pacific, vol. in. , p. 50. 



