XIV NOTES BY TITE EDITOR 



they also afford most important facilities for the discover) 7 of new 

 planets. They enable us to determine the variation and the position 

 of a moving body by a simple micrometrical measurement, or even 

 by ocular triangulation, and so render much more easy the detection 

 of those regular variations of place which enable us to pronounce the 

 moving body to be a planet. Induced by these considerations, and 

 stimulated by zeal for the advancement of his favorite science, Mr. 

 Cooper, of England, some eight years ago, undertook the formidable 

 task of determining the position of all the stars in the neighborhood 

 of the ecliptic to the twelfth magnitude inclusive. Mr. Cooper's cata- 

 logue now extends to five volumes, and is the result of upwards of 

 72,000 observations carried on uninterruptedly during eight years, 

 or at the rate of 9000 observations per annum. A singular circum- 

 stance attended the progress f this great undertaking, namely, the 

 disappearance of about seventy-seven stars which had been previously 

 observed, and whose positions had been noted. Of these, fifty had 

 been catalogued by Mr. Cooper in the earlier part of his labors, but 

 when afterwards sought for, were not to be seen ; the others had been 

 noted in the catalogues of foreign astronomers. This remarkable lact 

 of the disappearance of stai's, recently observed, has been confirmed 

 by M. Chacornac, of France, who has published eighteen charts of 

 the positions of ecliptic stars. It is of course possible that some cases 

 of supposed disappearance may only be apparent, and arise from the 

 errors of former observers, and perhaps, also, by the discovery cf 

 the small planets situated between Mars and Jupiter, which, at the 

 time of observation, were mi>taken for stars. But the greater num- 

 ber are, undoubtedly, real disappearances, -which can only be ac- 

 counted for by an actual variability in the stellar systems, whether 

 periodical or otherwise. The number of known variable stars - - those, 

 namely, whose brightness alternately increases and diminishes at 

 regular intervals has been greatly augmented since the attention of 

 astronomers has been directed to stars of inferior magnitude ; and it is 

 not improbable that the stars which have disappeared belong to this 

 class, and that they will, consequently, be found to reappear at some 

 future time. But it is highly improbable that all are of this class, 

 and, therefore, destined to become once more visible. If, on the 

 contrary, it be found that there are no permanent changes in the 

 stellar system, which are not compensated by opposite fluctuations, 

 these observations of Mr. Cooper, and others of a similar kind, made 

 by other astronomers, acquire an importance far beyond that belong- 

 ing to their immediate object, opening up, in fact, a new field of 

 astronomical inquiry, and new motives to" diligence and accuracy in 

 the arduous duty of mapping the stars. 



At the meeting of the American Association, Springfield, 1859, 

 Prof. Henry stated, that at the present time most of the telegraphic 

 companies south of New England and east of the Mississippi send to 



