THE QUESTION ENLARGED. 25 



even a god would have recoiled (Hipparchus ausus, rem etiam 

 Deo improbam, annumerare posteris Stellas)* 



Yet numerous doubts had already risen in the mind of 

 Hipparchus as to the accuracy of the number recognised. In 

 the first place, the ancients undoubtedly knew, as we do, that 

 the visual faculty is not the same in all individuals j that there 

 are some who, in the same celestial space, see more stars than 

 others. Many persons can discern up to stars of the seventh 

 magnitude, while with others the sight fails far within that 

 limit. The ancients must also have known, as we do, that, 

 for the enumeration to be complete, the sky must be observed 

 from all the points of the terrestrial surface on which man is 

 planted. Even in our own days the catalogues of the southern 

 heavens are far from being perfect. Finally, more than two 

 thousand years before the time of Galileo, Democritus had 

 already enunciated the opinion that the Milky Way was a mass 

 of innumerable stars. All these signs should have been 

 accepted as warnings against premature affirmations. 



The invention of telescopes suddenly enlarged the question, 

 and it became necessary to establish a line of demarcation 

 between the number of stars visible to the naked eye and the 

 number visible through the agency of the telescope. Arge- 

 lander, the author of the " Uranometria," has found that the 

 stars visible to the naked eye, over the entire surface of the 

 heavens, range from 5000 to 5800. Otto Struve, employing 

 Herschel's method of computation, has estimated at upwards 

 * Pliny, "Historia Naturalis," Book ii., 24. 



