OF NATURAL PHILOSOPHY. 279 



crease in our scale of dimension calls for a corre- 

 sponding enlargement of conception in all other 

 respects. The same reasoning which places the 

 stars at such immeasurable remoteness, exalts them 

 at the same time into glorious bodies, similar to, and 

 even far surpassing, our own sun, the centres per- 

 haps of other planetary systems, or fulfilling purposes 

 of which we can have no idea, from any analogy in 

 what passes immediately around us. 



(310.) The comparison of catalogues, published 

 at different periods, has given occasion to many 

 curious remarks, respecting changes both of place 

 and brightness among the stars, to the discovery of 

 variable ones which lose and recover their lustre 

 periodically, and to that of the disappearance of 

 several from the heavens so completely as to have 

 left no vestige discernible even by powerful tele- 

 scopes. In proportion as the construction of astro- 

 nomical and optical instruments has gone on im- 

 proving, our knowledge of the contents of the heavens 

 has undergone a corresponding extension, and, at 

 the same time, attained a degree of precision which 

 could not have been anticipated in former ages. 

 The places of all the principal stars in the northern 

 hemisphere, and of a great many in the southern, 

 are now known to a degree of nicety which must 

 infallibly detect any real motions that may exist 

 among them, and has in fact done so, in a great 

 many instances, some of them very remarkable 

 ones. 



(311.) It is only since a comparatively recent 

 date, however, that any great attention has been 

 bestowed on the smaller stars, among which there can 

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