since been open. On so technical a subject only an expert can 

 speak with confidence, and I am glad to be able to refer readers 

 to the critical remarks on de Saussure's meteorological work with 

 which my friend, Dr. H. R. Mill, has kindly furnished me. 1 



Professor Raoul Gautier, Professor of Astronomy, and now 

 Rector of the University of Geneva, has called my attention 

 to a particular observation made on the Col du Geant. He 

 writes : ' At this date the question of the atmospheric or 

 cosmic origin of shooting stars was still under discussion, and 

 they were commonly held to be produced in the lower regions 

 of our atmosphere. The great good sense and shrewdness of 

 de Saussure led him to make two crucial remarks : "I have 

 observed," he says, "all these stars above the horizon, and none 

 below ; this seems to me to prove that these meteors are only 

 formed in extremely lofty regions of the atmosphere." He goes 

 on : " The cause of these phenomena, though they are so frequent 

 and remarkable, appears to be still unknown. Even the upper 

 limit of their range is uncertain. It could, however, easily be 

 determined. In order to do this it would be enough for two 

 observers, placed at stations the distance between which was 

 known, to arrange to take simultaneous observations of all that 

 appeared on the same night, comparing them with known stars 

 and noting their characteristics and the precise moment of their 

 appearance. Their parallax would give their elevation and their 

 distance." This is precisely the method which some years later 

 was employed by Benzenberg and Brandes at Gottingen to 

 determine the height of the appearance of shooting stars (about 

 one hundred kilometres) and their velocity.' 



In his meteorological work de Saussure found frequent 

 occasion to display his ability as an inventor. Among the 

 instruments he constructed was the Hygrometer, with which he 

 settled the problem of moisture in the atmosphere. He also 

 contrived a Diaphanometer and a Cyanometer to test the relative 

 transparency of the air, and an Anemometer to ascertain the 

 force of the wind. He invented an apparatus for testing the 

 sun's heat ; he even attempted to apply ' bottled sunshine ' to 

 heating purposes. He devised a practical instrument for the 

 study of the evaporation of water and ice, and applied his 



1 See Dr. Mill's Note. 



