METEOROLOGICAL OBSERVATORIES. 163 



larly at the rate of about 1° 0. for each rise of 200 meters, which cor- 

 responds to 1° F. to 364 feet rise. 



The temperature of the air on mountain slopes is sensibly less than 

 in a free stratum of air at the same altitude as observed from a balloon. 

 M. Vallot has given in his Annals, as far as possible, all the results as 

 regards air pressure, moisture, temperature, wind, and weather gener- 

 ally, and he must be regarded as having made already, by the publica- 

 tion of his first volume, a real contribution to knowledge in a direction 

 in which comparatively little has been done. 



I must not leave the summit of Mont Blanc without showing you the 

 observing cabin which has been gallantly pitched by M. Janssen on 

 the very summit of the mountain, considerably higher, as you will have 

 seen by the photograph, than the more permanent observatory of M. 

 Vallot. The snow movements have for the present defeated M. Jans- 

 sen, but it is not likely he will give up the attempt. M. Eiffel has also 

 made an observing tunnel or gallery in the ice cap, and sundry timbers 

 and objects placed therein will in the nature of things slowly sink with 

 the glacier, and perhaps inform future ages of what has been done. 



EUROPEAN MOUNTAIN OBSERVATORIES. 



Time will not permit me to describe to you the other mountain 

 observatories of Europe. There are many, from the Sonnblick in the 

 Austrian Alps, where there is a well-found observatory at a height of 

 over 10,000 feet, to the establishment of our own Ben Nevis, which 

 only boasts the modest altitude of 4,406 feet. 



I show you a few pictures representing this last-named observatory 

 and its condition in mid-winter, when I think no one will envy the 



unfortunate observers who have to stay there, left severely alone. 



i 



AMERICAN MOUNTAIN OBSERVATORIES. 1 



This subject must not be quitted without mention of the observatory 

 which has been perched on the Andes by the enterprise of the authori- 

 ties of Harvard College in America. 



I show you two views of this by the kindness of Professor Pickering. 

 One shows the Arequipa station of the observatory at an altitude of 

 8,000 feet, while the other gives a view of the summit of El Misti in 

 Peru, with the meteorological shelters erected there for the accommo- 

 dation of the self-registering instruments, at the height of 19,200 feet 

 above the sea, constituting this the highest meteorological station in 

 the world. 



Most interesting results can not fail to arise from this gallant attempt 

 to pierce the clouds in search of knowledge. Mr. A. L". Eotch, of the 

 Blue Hill Observatory, Boston, United States, has constituted himself 



^ee Mountain Observatories in America and Europe, by Edward S. Holden. 8vo, 

 pp. 77. Smithsonian Miscellaneous Collections, Vol. XXXVII. Washington City, 

 1896. 



