APPENDIX. 389 



of these might with advantage be chosen on islands, and among 

 these the following may be suggested : — the Peak of Tenerifife, 

 Mauna Kea in the Sandwich Islands, Fusiyama in Japan, the 

 Piton de Neige in the island of Reunion, and Etna in Sicily. It 

 would add much to the value of these observations if in each 

 case there were a double series of stations, one series being on 

 the windward, the other on the leeward side of the mountain. 

 It would also be important to obtain observations at similar 

 series of stations in continental regions, removed from the im- 

 mediate influence of the sea. Pike's Peak in Colorado, which 

 already possesses an observing station at the summit, and 

 Mount Whitney in California, which Mr. Langley has selected 

 as eminently suited for an observatory, both offer many advan- 

 tages for the desired purpose. Another desirable station might 

 easily be found in the Caucasus, or in Armenia, and one or 

 more could be selected on the southern declivity of the Hima- 

 layes. In South America, where railways have been carried 

 to such great heights, it may be hoped that regular observations 

 may at some future time be secured at the successive railway 

 stations. It would be worthy of the enlightened governments 

 of Chili and Argentaria to make a commencement, by providing 

 for such a series being obtained at the stations on the railway 

 now in course of construction over the Uspallata Pass. 



For the realization of most of these desires, as well as many 

 others affecting the progress of human knowledge, and the 

 general welfare of our race, we must be content to await the 

 advent of a happier era, when the fruits of industry, and 

 the efforts of rulers, shall no longer be mainly devoted to the 

 maintenance and development of the arts of destruction. 



While awaiting such additional knowledge as may hereafter 

 be obtained, it is necessary in the mean time to form some 

 provisional hypothesis on which to base the formulse for deter- 

 mining the difference of heights of two stations, by barometric 

 observations, and for ascertaining the amount of atmospheric 

 refraction; and the subject might with advantage be discussed 

 at a congress of scientific men. I have no authority to decide 

 on a question of such difficulty, nor do I pretend to be 

 thoroughly versed in the somewhat voluminous literature of 

 the subject. I may remark, however, that in one of the 

 fullest and most elaborate works by recent writers, Dr. Riihl- 



