162 METEOROLOGICAL OBSERVATORIES. 



I do my work as much on tlie actual snowy summit, which is quite near, 

 as in the study which I Lave built. Life is not easy at these heights, 

 for one has to contend with mountain sickness, but I have become so 

 accustomed to the conditions that 1 can work there as well as when 

 below, even when there are storms going on during the day or night. 



Some few scientific men have also made use of the observatory, but 

 at rare intervals. 



After I had constructed my observatory, M. Janssen came here and 

 worked, but he wished to make another of his own, and he placed it on 

 the actual snowy summit of the mountain. He began in 1893, and con- 

 tinued during 1894 and 1895. It is nearly finished, but not yet com- 

 ] detely furnished with instruments, so that up to the present no scientific 

 Avork has been done. M. Janssen has abandoned the idea of perma- 

 nently entertaining observers there. He has had constructed a superb 

 meteorograph, which has this season been safely placed on the summit. 



Unfortunately his observatory is placed on the snow, and has there- 

 fore no stability, for snow has continual movements of its own, and the 

 clocks of the instruments are stopped. They have seldom gone for more 

 than three days at a time. M. Janssen is very much disappointed, but 

 he has told me that he intends to try other means. It will thus be some 

 time before this observatory can give any results. 



From an astronomical point of view, not much further progress has 

 been made. The workmen who ascended to erect the telescope were too 

 unwell to do the work. Two astronomical expeditions have not been 

 any more fortunate, for the leaders of the same were seized with illness, 

 and could do nothing, although they " saved the situation" by working 

 at the lower level of 3,000 meters at the "Grand Mulet's" rocks. 



To do any work at the summit, it is necessary to have been accus- 

 tomed to exist at great elevations. 



I am happy to be of any use to you, and I am desirous to see some 

 English students working in my observatory. I offer my services to 

 you and to your Society, as it is my principle not solely to work for 

 myself, but to facilitate the labors of others by all possible means. 

 Yours, etc., 



Joseph Yallot. 



In his Annals, M. Yallot further says on the subject of establishing 

 observatories on such elevated spots: 



It is necessary to have beeu half-blinded by the snow, to have felt the 

 thousand stingings of the atmospheric electricity, to have crawled pros- 

 trate over the soft snow, to have been blown over by the wind, and to 

 have couched down before avalanches, ere one can give a correct account 

 of the terrible intensity of the weather conditions at these great alti- 

 tudes. It is after this that we comprehend the powerful impulses given 

 to the upper regions of the air, and which are only feebly transmitted to 

 the lower levels through an enormous mattress of atmosphere and 

 vapor which serves to deaden its movements and falsify its indications. 



Among the results already to be mentioned as coming from the Mont 

 Blanc observations the following may be here enumerated, though a 

 much longer list might be made. 



The wave of diurnal variation of temperature is about one-third of 

 the amplitude of that at Chamounix. 



The experiences at the Mont Blanc Observatory confirm those of Mr. 

 James Glaisher made in balloon ascents, the cold increases very regu- 



