The Earth as seen from the Moon. 327 



the two hemispheres, if, as is possible, the one we do not see, 

 possesses water and air. After some other remarks he observes, 

 that the astronomy of the Selenites must appear so compli- 

 cated as to require the greatest penetration for its true ex- 

 planation. " They behold themselves motionless in the centre 

 of the universe, they see the sun perform its circuit in 29-|- 

 days, and the stars in 27 j days. Those who see the earth 

 will perceive that although it appears almost immoveable in 

 the same part of space, it goes round the sky in 29 days. 

 They would ascribe these movements to the sky and to the 

 earth. As for thinking that they moved, and that this earth 

 was the centre of their movements, and that the sun was the 

 centre of those of the earth and planets ; this is a notion to 

 which it would be extremely difficult for them to attain. 

 Celestial appearances are not so complicated as seen from any 

 star as from the satellites." 



" Less favoured than the Subvolvian Selenites, who in their 

 transition from day to night pass only from an intense to a 

 feeble light, the Privolvians have a complete night of fifteen 

 days. It follows from experiments of Bouguer, M. Lambert, 

 and even from the theory of Robert Smith, that the mean 

 relation of solar to lunar light is as 300,000 to 1 ; the mean 

 relation between sun light and fall earth light for the Selenites 

 would be as 23,000 to 1. Those who inhabit the opposite 

 hemisphere will have no illumination during their night. But 

 perhaps under their unknown atmosphere they light up arti- 

 ficial suns for half the year ; perhaps nature furnishes them 

 with a special illumination, like the Auroras that illuminate 

 our polar regions ; perhaps their eyes are constructed for 

 nocturnal life ; perhaps they sleep like marmots during their 

 dark winter of half a month. These are all may bes ; but we 

 cannot doubt that nature has established the Selenites com- 

 fortably in their homes ; and if one of them came here for the 

 winter he would be astonished with the enormous terrestrial 

 globe that gives us a profusion of day and night, and, like a great 

 child, makes us play at hido and seek all our lives." — Cosmos. 



