260 THE MONT BLANC OBSERVATORY. 



The rectangular base measures 10 by 5 meters. The upper floor, which 

 will be devoted to the observations, is covered with a flat roof, toward 

 which ascent is made by a spiral staircase leading from the basement 

 upwards through the whole building, and above the flat roof to a small 

 platform destined for meteorological observations. 



The whole observatory has double walls to protect the observers 

 against the cold. The windows and doors are also double, and pro- 

 vided on the outside with shutters closing hermetically. The floor is 

 made of double planks, and furnished with trap doors giving access to 

 the snow supporting the observatory, and to tlie screw jacks placed 

 iu position for adjusting the level of the building in case the snow 

 should yield. The building will be provided with heating apparatus 

 and all the furniture necessary to make habitation at such an altitude 

 possible. 



Up to the present the observatory has been transported in parts to 

 Chamoumx. On the Grands Mulcts a cottage has been erected for the 

 use of the workmen and for storing the things destined for the observ- 

 atory. 



On the Grand Rocher Rouge another cottage has been built, only 

 300 meters below the summit, m which the workers and observers 

 can, if necessary, take refuge. Three-quarters of tlie materials for 

 the observatory have been transported to the Grands-Mulets (3,000 

 meters) and the rest to the Rocher Rogue (4,500 meters). 



Next year the erection on the summit will be carried out. An 

 astronomical dome, which is to complete the observatory, will also be 

 taken in hand. The work done up to now has been carried out under 

 great difficulties, owing to the fact that everything had to be carried by 

 hand. But no accident has, so far, marred the success. 



Dr. Capus, who accompanied M. Bonvalot in his well-known expedi- 

 tion to the Pamir, has promised his assistance for certain observations. 

 But the observatory will be international and open to all observers 

 who wish to work there. 



THK OBSERVATORY ON MOUNT BLANC* 



As briefly announced in onr notes last week. Dr. Janssen has recently 

 visited the observatory on Mount Blanc. In the current Compte.s ]\en 

 dus he gives an account of the expedition from a scientific point of 

 view, and the following is a translation of his description : 



Weleft Chamonix on September 8, at 7 a.m., and arrived at the sum- 

 mit on Se[)tember 11, at 2:30 p. m. Tlie observatory was then in front 

 of us. This construction has several floors, of which the framework, 

 formed by large and massive beams crossed in all directions in order to 

 insure the rigidity of the whole, produces a deep im[>iession upon the 



I 



From Nature, October 5, 18it3; vol.XLyiii, p. 519. 



