34 COSMOS. 



we may with great probability assume, not only with our own 

 Sun, but also with all the other luminous suns of the firma- 

 ment. The important discovery of the appreciable resistance 

 which a fluid filling the realms of space is capable of oppos- 

 ing to a comet having a period of revolution of five years, 

 has been perfectly confirmed by the exact accordance of 

 numerical relations. Conclusions based upon analogies may 

 fill up a portion of the vast chasm which separates the certain 

 results of a mathematical natural philosophy from conjec- 

 tures verging on the extreme, and therefore obscure and 

 barren confines of all scientific development of mind. 



From the infinity of space, an infinity, however, doubted 

 by Aristotle, 10 follows the idea of its immeasurability. Se- 

 parate portions only have been rendered accessible to measure- 

 ment, and the numerical results, which far exceed the grasp 

 of our comprehension, become a source of mere puerile grati- 

 fication to those who delight in high numbers, and imagine 

 that the sublimity of astronomical studies may be heightened 

 by astounding and terrific images of physical magnitude. The 

 distance of 61 Cygni from the Sun is 657000 semi-diameters 

 of the Earth's orbit; a distance which light takes rather more 

 than ten years to traverse, whilst it passes from the Sun to 

 the Earth in 8' 17"'78. Sir John Herschel conjectures, from 

 his ingenious combination of photometric calculations, 11 that 

 if the stars in the great circle of the Milky Way which he 

 saw in the field of his twenty-feet telescope were newly-arisen 

 luminous cosmical bodies, they would have required 2000 

 years to transmit to us the first ray of light. All attempts to 

 present such numerical relations fail, either from the immen- 

 sity of the unit by which they must be measured, or from 



10 Aristot. de Ccelo, 1, 7, p. 276 ; Bekker. 



11 Sir John Herschel, Outlines of Astronomy, 1849, 803, 

 p. 541. 



