30 COSMOS. 



by Aristotle*- — follows the idea of its immeasurability. Sep< 

 arate portions only have been rendered accessible to meas- 

 urement, and the numerical results, which far exceed the 

 grasp of our comprehension, become a source of mere puerile 

 gratification to those who delight in high numbers, and im- 

 agine that the sublimity of astronomical studies may be 

 heightened by astounding and terrific images of physical mag- 

 nitude. The distance of 61 Cygni from the Sun is 657,000 

 semi-diameters of the Earth's orbit ; a distance which light 

 takes rather more than ten years to traverse, while it passes 

 from the Sun to the Earth in 8' 17"-78. Sir John Herschel 

 conjectures, from his ingenious combination of photometric 

 calculations,! 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 fight 

 All attempts to present such numerical relations fail, either 

 from the immensity of the unit by which they must be meas- 

 ured, or from the high number yielded by the repetition of 

 this unit. Bessel$ very truly observes that " the distance 

 which light traverses in a year is not more appreciable to 

 us than the distance which it traverses in ten years. There- 

 fore every endeavor must fail to convey to the mind any 

 idea of a magnitude exceeding those that are accessible on 

 the earth." This overpowering force of numbers is as clear- 

 ly manifested in the smallest organisms of animal life as in 

 the milky way of those self-luminous suns which we call 

 fixed stars. What masses of Polythalamiae are inclosed, ac- 

 cording to Ehrenberg, in one thin stratum of chalk ! This 

 eminent investigator of nature asserts that one cubic inch of 

 the Bilin polishing slate, which constitutes a sort of mount- 

 ain cap forty feet in height, contains 41,000 millions of the 

 microscopic Galionella dista?is ; while the same volume con- 

 tains more than 1 billion 750,000 millions of distinct indi- 

 viduals of Galionella ferrugi?iea.k Such estimates remind 

 us of the treatise named Arenarius (ipafifiiT^g) of Archime- 

 des — of the sand-grains which might fill the universe of 

 space ! If the starry heavens, by incalculable numbers, 

 magnitude, space, duration, and length of periods, impress 



* Aristot., De Ccelo, 1, 7, p. 276. Bekker. 



t Sir John Herschel, Outlines of Astronomy, 1849, $ 803, p. 541. 

 t Bessel, in Schumacher's Jahrbuch fur 1839, s. 50. 

 $ Ehrenberg, Abhandl. der Berl. Akad., 1838, s. 59; also in his Lift* 

 nonsthiere, s. 170. 



