great number of alterations of stars that we are certain have 

 happened within the last two centuries, and the much greater 

 number that we have reason to suspect to have taken place, 

 are curious features in the history of the heavens, as curious as the 

 slow wearing away of the landmarks of our earth on mountains, on 

 river banks, on ocean shores. If we consider how little attention has 

 formerly been paid to this subject, and that most of the observations 

 we have are of a very late date, it would perhaps not appear extra- 

 ordinary were we to admit the number of alterations, that have prob- 

 ably happened to different stars, within our own time, to be a hundred. 



WILLIAM HERSCHEL. 



