190 ASTRONOMICAL HISTORY. 



But with respect to the number, magnitude, configura 

 tion, and remoteness of the stars, with the exception of the 

 phenomena and historical inquiries, of which we shall 

 speak by and by, the problems which philosophy offers are 

 generally simple. With respect to their number, too, there 

 follows another question : whether that be the true number 

 of the stars which is visible, and which has been set down 

 and described by the labours of Hipparchus, and comprised 

 within the plan of the celestial globe. For it is but a barren 

 reason which is assigned for the incalculable number of 

 stars, usually hid, and as it were imperceptible, which are com 

 monly seen in winter, particularly in clear nights, namely, 

 that these appearances are not smaller stars, but emanations, 

 scintillse, and as it were darts emitted by known stars; 

 besides, there has been a new enumeration of the host of 

 heaven by Galileo, not only in that cohort which is dis 

 tinguished by the name of the milky way, but also amidst 

 the stations and system of the planets. Now stars become 

 imperceptible either on account of the minuteness of their 

 size, or their opacity (the term tenuity we do not much 

 approve of, since pure flame is a body of the most subtle 

 tenuity), or on account of their remoteness and distance. 

 The question with respect to the superflux of stars, created 

 by the production of new ones, we refer to the part w r hich 

 treats of comets. 



As regards the magnitude of the stars, the visible mag 

 nitude belongs to the general phenomena, the real to the 

 philosophical inquiry comprehended only in our twelfth 

 problem : What are the real dimensions of each star, 

 either discovered by measurement, or, if not, by compari 

 son ? for it is easier to discover and demonstrate that the 

 globe of the moon is less than the globe of earth, than that 

 the globe of the moon is a mile round. We must then use 

 all trial and exertion to ascertain their exact dimensions ; 

 if these cannot be had, we must make use of their com 

 parative. 



Now the magnitudes of the stars are either taken and 

 inferred from their eclipses and obscurations, or from the 

 bounds to which they extend their light, and the other 

 properties which each of these bodies, in proportion to 

 their magnitude, emit and propagate; or, lastly, by the 

 harmony of the universe, which confines and limits, by a 

 certain necessity, the parts of the homogeneous bodies. 

 For we must not rest upon the accounts given by astrono 

 mers of the bare magnitude of the stars, (though they have 



