A VOYAGE TO THE RINGED PLANET. 83 



level in which Saturn travels as to the plane of the 

 ring-system (in which plane, as you are aware, Mimas 

 circles), they have two chief seasonal influences. During 

 the long Mimasian year (the same, of course, as the 

 Saturnian) the sun's midday altitude changes much as 

 on the earth; but the four quarters of the year are 

 each rather more than seven of our years in length. 

 These changes do not greatly affect the Mimasians, 

 though they commonly live some ten or twelve years, 

 that is from about 300 to about 350 of our years. (X. 

 supposes their remarkable longevity to be due to the 

 slowness and limited extent of their respiration.) Their 

 chief season-ruler is Saturn himself, who supplies them 

 with an enormous amount of heat. Indeed, the heat 

 supplied by Saturn is so great that (as we afterwards 

 learned) the inhabitants of Tethys, Dione, and Ehea 

 hold life to be impossible not only in Mimas but in 

 Enceladus, the next in order of distance from Saturn. 

 It will be understood how important a part the heat of 

 Saturn plays in the economy of Mimas, when I mention 

 that he looks about nine hundred times as large as the 

 sun appears to us. He does not indeed shine very con- 

 spicuously, the light he gives being such as I have 

 already described in speaking of our approach to his 

 globe. But the Mimasians have to shade their heat- 

 eyes (so to name the feature already mentioned) when 

 the vast orb of Saturn is in the fulness of his meridian 

 heat-glow. Particularly is this the case when he is high 

 above the horizon at this heat-noon. For, owing to the 

 inclination of the axis of Mimas to the plane in which 



a 2 



