DIRECTIONS FOR OBSERVING 



THE SCINTILLATION OF THE STARS. 



By CH. DUFOUR, 

 professor at morges, switzerland. 



TRANSLATED FOR THE SMITHSONIAN INSTITUTION, FEOM THE " REPERTORIUM FUR MEIEOROLOGIE, 



ETC.: DORPAT, 1859. 



Even to the most recent times the sciiitilliDtion of the stars has not 

 formed the subject of any series of observations. We find here and 

 there, it is true, some isolated observations, and a few persons have 

 proposed different explanations of this phenomenon, but as yet no 

 course of investigation had been seriously prosecuted. I may claim 

 to be the first who undertook a labor of this kind. My observations 

 at Morges in 1852 were at first but a succession of attempts, but from 

 1853 to the present moment I have allowed no evening, when the 

 stars could be seen, to pass without carefully observing the scintilla- 

 tion. And now, after the dedication of six years to such inquiries, I 

 feel authorized to pronounce that this study is important, and well 

 deserves to occupy a place among meteorological observations. 



But in order that the results may be general and more complete, it 

 is desirable that systematic observations analogous to those which I 

 have undertaken should be prosecuted elsewhere in other climates 

 and unde'r varied meteorological circumstances. There can, at pres- 

 ent, but four stations be counted where I am justified in hoping that 

 this incjuiry has been entered upon and will be persistently carried 

 on: 



1. Morges, Switzerland, 46° 30' north latitude, 4° 9' east longitude 

 from Paris. Since 1853 I have taken at this station nearly 24,000 > 

 observations of scintillation. The principal results thus far obtained I 

 from these numerous observations have been published either in the ■ 

 ' ' Comptes Rendus ' ' of the Academy of Belgium, or in those of the ■ 

 Academy of Paris, or in the Notices of the Astronomical Society of I: 

 London, or in the Bulletins of the Vaudoise Society of the Natural I 

 Sciences. I propose soon to communicate some of these observations ^ 

 to the "Repertorium,"' <fec., as a sequel and complement to the pres- 

 ent directions: 



2. The great St. Bernard, in the Alps, at an altitude of 2,480 j 

 meters. The monks, who pass the whole year in these elevated re- i 

 gions on the borders of perpetual snow, have consented to continue I 



