760 ASTRONOMICAL NOTES. 



compare this result with the work of other celebrated astronomers. I copy 

 them from the paper of Prof H. in Ast.^Nach., No. 2,174.^ The letter Y 

 denotes the angular distance of the centre of the spot from the south pole 

 of Mars. 



Herschel 1783, v= 8. 8° Linseer 1862, v= 20.10° 



Bessel 1830, v= 8. 6 Kaiser 1862, v= 4.16 



Beer and Miidler, 1837, v= 12. Hall 1877, v= 5.11 



Secchi 1857, v= 17.42 



The anomaly above mentioned, with other reasons, has led some astron- 

 omers of late to question the long admitted theory that the spots are 

 accumulations of snow and ice. At the meeting of the Eoyal Astronomical 

 Society, of London, Nov. 9, 1877, a paper was read by Mr. Brett, tending to 

 show that the received hypothesis of similarity in physical conditions be- 

 tween the earth and Mars is utterly untenable. The fundamental fact 

 on which he reasons is the alleged absence of clouds in the envelope of the 

 planet. He also asserted that the spot was not continuous with the surface 

 of the planet, but lay far above it. This he concludes because no dark patch 

 on the planet ever reaches to the limb, while the white south polar spot pro- 

 truded beyond it. He suggested that the south polar spot is a permanent 

 cloud, and the only real cloud in Mars. Prof. Hall's observations, however, 

 made on the clearest nights and with the largest refractor now in use, seem 

 to indicate very distinct markings or notches on the edge of the spot, and 

 that it is really a depression in the surface of the planet. The hypothesis 

 of a depression in the surface at once rids us of the anomaly of eccentric 

 poles of cold, and seems more reasonable than that of one solitary and per- 

 manent cloud in the upper atmosphere of the planet. 



I am gratified to add that Prof. Hall has received from the Academy of 

 Sciences, Paris, the celebrated Lalando prize. No better evidence could 

 possibly be afforded of the high estimate placed on his discovery of the Mars 

 moons. It is the judgment of the successors of such men as Lalando, Lap- 

 lace, Delambre and Leverrier. 



I am privately informed that Prof. Hall has^selected for the new satellites 

 names, significant at once of their attendance on Mars and of their rapid 

 rotation. The outer satellite is to be named Leimos, and the inner one 

 Phobos. These personations of terror and fear, in the mythology of Homer 

 and Hesiod, are always represented as attendant on Mars, (Ares in Grerman) 

 the god of desolation and war — sometimes they are mentioned as his sons, 

 at other times as his charioteers, and even as his fiery steeds. In Homer, 

 Phobos personified, means flight, the resultant of Deimos terror. So Liddell 

 and Scott, and so Pope has it. 



Iliad, Book XV, line 119: 



"With that he gives command to Fear and Flight, 

 To join his rapid coursers for the fight ; 

 Then, grim in arms, with hasty vengeance fliesr— 

 A.rras that reflect a radiance thro' the skies." 



