NOTES. 



1840. If the parallax of Alcyone were really 0"'0065, then its distance 

 would amount to 31 million times the semi-diameter of the Earth's orbit ; 

 thus it would be fifty times more distant from us than the double star 61 

 Cygni, according to Bessel's earliest determination. Light which comes from 

 the Sun to the Earth in 8' 18*'2, would require 500 years to travel from 

 Alcyone to the Earth. The Imagination of the Greeks delighted in wild 

 estimations of space fallen through. In Hesiod's Theogony, v. 722 725, 

 it is said, speaking of the fall of the Titans to Tartarus, " When once an 

 iron anvil fell from heaven, nine days and nights it fell, and on the tenth it 

 reached the Earth." To this fall taking place in 777600 seconds of time, 

 the corresponding distance (taking into account, according to Galle's calcu- 

 lation, the great decrease of the Earth's attractive force at planetary dis- 

 tances) is 77356 German (309424 English) geographical miles, or once and 

 a half the distance from the Moon to the Earth. But according to Homer, 

 H. i. 952, Hephsestos fell down to Lemnos in only one day, and merely " still 

 breathed a little." The length of the chain hanging down from Olympus to 

 the Earth, by which all the gods were to essay to draw Zeus down (II. viii. 

 18), is left indefinite. It is an image intended to express, not the height of 

 heaven, but the strength and surpassing might of Jupiter. 



( 32S ) p. 198. Compare the doubts expressed by Peters in Schum. Astr. 

 Nachr. 1849, S. 661, and by Sir John Herschel in the Outlines of Astr. 

 p. 589. "In the present defective state of our knowledge respecting the 

 proper motion of the smaller Stars, we cannot but regard all attempts of the 

 kind as to a certain extent premature, though by no means to be discouraged 

 as forerunners of something more decisive." 



( 329 ) p. 199. Compare Kosmos, Bd. i. S. 152154 and 414 (Eng. ed. 

 p. 136 138, and xxxvii.) (Struve iiber Doppelsterne nach Dorpater 

 Micrometer-Messungen von 1824 bis 1837, S. 11). 



C 30 ) p. 200. Kosmos, Bd. iii. S. 6467, 110113 and"l66 168 (Eng. 

 ed. p. 47 50, and 108 110). As remarkable examples of visual power in 

 particular individuals, I may mention that Kepler's instructor, Mostlin, saw 

 with the naked eye 14, and some of the Ancients 9, stars in the group of 

 the Pleiades. (Miidler, Untersuch. iiber die Fixstern-Systeme, Th. ii. S. 36.) 



(3 31 ) p. 200. Kosmos, Bd. iii. S. 271 (Eng. ed. p. 185.) Dr. Gregory of 

 Edinburgh also recommended the same method in 1675 (33 years therefore 

 after Galileo's death) ; compare Thomas Birch, Hist, of the Royal Society, 

 Vol. iii. 1757, p. 225. Bradley (1748) alludes to this method at the end of 

 his celebrated treatise on Nutation. 



