188 ASTRONOMICAL HISTORY. 



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to the increase and lessening of the stars as bodies, though 

 the phenomena which may occasion uncertainty on the 

 subject are very few. 



For first of all, no instance, or any analogous facts in 

 human experience favour the inquiry; since our globe of 



earth and water does not seem subject in its mass to any 



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conspicuous augmentation or diminution, but preserves its 



bulk and quantity. But, it may be said, the stars appear 

 to our view sometimes of larger, sometimes of smaller size. 

 This is true, but that larger or smaller dimension of a star 

 is ascribable either to its proximity or remoteness; or in their 

 apogees and perigees, in the case of the planets ; or to the 

 constitution of the medium of vision. So far as this arises 

 from the constitution of the medium, it is easily discrimi 

 nated, because that changes not the appearance of one star 

 in particular, but of all equally : as happens on winter nights 

 in a keen frost, when the stars appear of increased magni 

 tude, because the vapours of the earth both mount in less 

 quantity and are dissipated more powerfully, and the whole 

 body of the atmosphere is to a certain degree condensed, 

 and approaches an aqueous or chrystalline character, which 

 exhibits objects in increased dimension. But if it were 

 some particular intervention of vapours between our vision 

 and some given star, magnifying the appearance of the 

 star (which we frequently and plainly see happening in the 

 case of the sun, and moon, and other heavenly bodies), 

 that appearance can neither impose upon us in itself, nor 

 does the star follow and move with the body of the vapour, 

 but is quickly extricated from it, and resumes its usual 

 appearance. But though these things are so, yet since 

 both formerly, in ancient times, and now also in our own 

 age, a great change, much noted and celebrated, has taken 

 place in the star Venus, in its magnitude, colour, and even 

 figure ; and since a change which always and regularly 

 attends a given star, and is seen to move about with its 

 body, ought to be considered as necessarily existing in the 

 star itself, and not in the medium of vision ; and since, 

 in consequence of the neglect of observations, many re 

 markable phenomena, which take place in heaven are passed 

 by unheeded, and are lost to us : we think it right to enter 

 tain this second branch of our question. 



Of the same kind is another part of our inquiry, whether, 

 during the long lapse of ages, stars are produced and de 

 composed ? not but that the multitude of facts which invite 

 this question is more copious and sufficient, than on that 



