176 ASTRONOMY ON MONT BLANC. 



meters), Briancon (1,298 meters), Puy de Dome (1,467 meters), Mont 

 Aigoiml (1,554 meters), Mont Ventoux (1,900 meters), Mo)\t 

 Mounier (2,740 meters), Pic du Midi (2,859 meters). The station 

 on Mont Mounier is also utilized for astronomical purposes. It is 

 believed by Messrs. Baillaud and H. Bourget that the Pic du Midi, 

 where indeed there are some instruments, may become an excellent 

 station for the astronomers. There should be added to this list the 

 observatory which J. Vallot has constructed on Mont Blanc, upon 

 the Bosses du Dromadaire, at an altitude of 4,350 meters. Estab- 

 lished in 1890, moved and enlarged in 1898, it has rendered valuable 

 service, which the Academic des Sciences in 1897 recognized by the 

 award of the grand prize in physical science. The results of the 

 work of Vallot and his assistants have been published by him in the 

 Annales de TObservatoire meteorologique, physique et glaciaire du 

 Mont Blanc, which form six quarto volumes. But the present paper 

 is devoted to the subject of astronomy and it is time to return to M. 

 Janssen. 



In his first ascent of Mont Blanc, in October, 1888, he did not pro- 

 ceed beyond the inn at Grands Mulcts, at the altitude of 3,000 meters, 

 situated on the rocks at the junction of the Bossons and Tacconaz 

 glaciers. At this time of the year the inn was already abandoned, 

 and there had recently been a heavy fall of snow which had effaced 

 the trail, hidden the crevasses, and rendered the ascent very difficult. 

 Owing to these obstacles thirteen hours were consumed in reaching 

 the chalet of Grands Mulcts by a route which in the favorable sea- 

 son is traversed in four hours, and the travelers arrived greatly 

 exhausted. Accordingly, when two years later Janssen determined to 

 try to reach the summit he discarded all thought of ascending on 

 foot and devised a sledge somewhat similar to those of Lapland. The 

 guides were ill pleased with this innovation ; but at length, on August 

 17, 1890. at 7 o'clock in the morning, Janssen left Chamonix in 

 company with Durier and 22 guides and porters, reaching the 

 chalet of Pierre Pointue about 10 o'clock and the inn at Grands 

 Mulcts at half past 5. On the next morning at 5 o'clock they left 

 Grands Mulcts, 12 guides dragging the sledge and carefully safe- 

 guarding against accidents, they reached about an hour after noon the 

 station at des Bosses which Vallot had constructed. Here it was 

 proposed to pass the night and resume the ascent the next morning, 

 but in the night the weather changed suddenly, and a terrible storm 

 burst upon them. It was the forerunner of the cyclone of August 

 19. They were obliged to wait three days, and Janssen had oppor- 

 tunity to reflect upon the advantage of a meteorological observatory 

 well equipped with long-running self -registering apparatus in this 

 high region, where the atmosphere disturbances are found in all their 



