28 MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 



an excellent test of the purity of the sky at great altitudes, and gives a 

 numerical measure of it. 



From Professor Cornu's Alpine observations made in 1879, the 

 result was that an elevation of 868 metres (2848 feet) increased the 

 upper limit of the solar photographic spectrum by one unit of Ang- 

 strom's scale {i. e., by one millionth of 1 mm.). The observations of 

 Dr. Simony were made at two stations on Teneriife, at Alta- Vista 

 (10,702 feet), and at the summit (12,198 feet). Professor Cornu's 

 map made at Courtenay (170 metres, 558 feet, above sea) served as a 

 basis of comparison, and the comparison showed that the gain at Ten- 

 eriffe in 1888 was substantially the same as that obtained in the earlier 

 Alpine observations. Professor Cornu's conclusion is "that very little 

 is to be gained [in this particular research] by transporting a spectro- 

 graph to high mountain stations ; the amount of the gain appears to be 

 less and less as greater elevations are reached." In spite of the small 

 benefit, the great interest which attaches to the subject makes it very 

 desirable that these experiments should be repeated at the summit of 

 Mt. Blanc, " especially if the observer can remain sufficiently long at 

 that great height." 



PROPOSED RAILWAY TO THE SUMMIT OF MT. BLANC. 



The scheme for a railroad to the summit of the Jungfrau has stimu- 

 lated two or three eminent French engineers to propose the greatest of 

 all tasks of this kind — namely, a railroad, or, rather, an elevator, to 

 the top of Mt. Blanc. The line would commence at the Miage Eavine, 

 above Saint-G-ervais, and at once be carried through a tunnel four and 

 a half miles in length. From this point a vertical shaft 9100 feet in 

 height would bring the traveller to the summit. The engineers are 

 not inclined to underrate the difficulties of the scheme. The height of 

 the vertical shaft will be more than double any now in existence. It is 

 said, however, that the road would not cost more than 9,000,000 francs. 



It would be easy to quote from many accounts of ascensions of Mt. 

 Blanc to show the real dangers which still remain and which always 

 will attach to this journey. The latest account will serve the purpose 

 as well as another — and in what follows I shall give a few paragraphs 

 from Mr. Garrett Serviss' recital of his ascent to the summit in 

 August, 1895. In early August Mr. Serviss ascended as far as the 

 refuge hut at des Bosses, but was obliged to return on account of a 

 terrific storm of snow and wind. The successful journey was made at 

 the end of the same month. Two of the illustrations in this section 

 are taken from Mr. Serviss' excellent article in McGlure's Magazine 

 for May, 1896. 



