Prof. Gautier on recent Researches relating to Nebula. 103 
of that year, and published in the “ Monthly Notices,” vol. xvii, 
pp. 225-230." 
Struve begins by pointing out the change in the brillianey of 
different small stars situated in the nebula of Orion, a variation 
which he has shown either by comparison of his observations 
with those of other astronomers, or in the progress even of his 
Own observations. 
“The existence,” says Struve, ‘of so many variable stars in 
So small a space of the central part of the most curious nebula 
in the heavens, would naturally lead us to suppose that these 
phenomena are intimately connected with the mysterious nature 
of this body. ... Admitting that the rapid changes of light ob- 
Served in these small stars, either in the region called Huygens 
or in that called Subnebulosa, may be connected with the nature 
of the nebula, one would expect in like manner to observe chan- 
8&8 In the appearances of the nebula and in the distribution of 
the nebulous matter. But observations of this kind are subject 
ie lead to results which can be regarded as certain. The op- 
cal power of the telescope, the transparency of the atmosphere, 
(Varying at different stations), the peculiarities of the eye of the 
“Xistence of progressive changes, but it will never be possible to 
demonstrate in this manner those changes which take place in 
short intervals of time. But the rapid variations of light in the 
118 require us to give attention to similar changes, pee S pe- 
t 1s thus to 
changes of this kind that we ought a Dog 4 to direct our 
sttention, and we shall be better able to prove their existence 
es have had . : : Beal Ee ee 
of var; 1 occasion to mention the labors of Struve in an article upon the: 
erable brightness, published in the Bibliotheque Universelle, for September and 
ineaa ce (Archives, tome xxxvi, p. 5 and 89). M. Otto Struve has recently 
father as director of the great Russian Observatory of Pulkova. 
