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Changes that happen to the fixed Stars. 
star itself will in every respect pass for one of that magnitude, 
when compared to a mental standard taken from other stars of 
the same author. Nor can its being brighter than stars which 
have a magnitude of a superior lustre affixed to them, do more 
than raise a considerable suspicion of a change. But as this 
subject will occur again hereafter, and as it must be sufficiently 
apparent that the present method of expressing the brightness 
of the stars is very defective, we now proceed to propose a dif- 
ferent one. 
I place each star, instead of giving its magnitude, into a 
short series, constructed upon the order of brightness of the 
nearest proper stars. For instance, to express the lustre of D, 
I say CDE. By this short notation, instead of referring the 
star D to an imaginary uncertain standard, I refer it to a 
precise, and determined, existing one. C is a star that has a 
greater lustre than D ; and E is another of less brightness 
than D. Both C and E are neighbouring stars, chosen in 
such a manner that I may see them at the same time with D, 
and therefore may be able to compare them properly. The 
lustre of C is in the same manner ascertained by BCD ; that 
of B by ABC ; and also the brightness of E by DEF ; and 
that of F by EFG. 
That this is the most natural, as well as the most effectual 
Way to express the brightness of a star, and by that means to 
detect any change that may happen in its lustre, will appear, 
when we consider what is requisite to ascertain such a change. 
We can certainly not wish for a more decisive evidence, than 
to be assured, by actual inspection, that a certain star is now no 
longer more or less bright than such other stars to which it 
has been formerly compared ; provided we are at the same 
