424 LECTURE XLIV. 



has observed a constant appearance of two bright spots or circles near the 

 poles of Mars, which he attributes to the ice and snow perpetually sur- 

 rounding them. It is not, however, probable that water could remain fluid 

 in any part of Mars, and even quicksilver and alcohol would, perhaps, be 

 frozen in his temperate climates. It is pretty certain that Mars has an 

 atmosphere, and his dark spots seem to be occasioned by clouds : this 

 atmosphere may, perhaps, also be the cause of the ruddy hue of his 

 light. 



It appears to be doubtful, whether either of the three little planets newly 

 discovered can be sufficiently solid, to give a firm footing to any material 

 beings : we should probably weigh only a few pounds each if transported 

 there. According to Dr. Herschel's opinion, neither Ceres nor Pallas is 

 much larger than a good Scotch estate, although they must, sometimes, 

 appear to each other as planets of a most respectable size. The light 

 reflected from Ceres is of a more ruddy hue than that of Pallas : both of 

 these planets are attended by more or less of a nebulosity, proceeding, per- 

 haps, from copious atmospheres ; and in this respect, as well as in the great 

 inclination of their orbits, they appear to have some affinity to comets. 

 It is tolerably certain that neither of them is 200 miles in diameter ; and 

 Juno is also probably about the same size. 



It is obvious that the most striking features of the heavens, when con- 

 templated from Jupiter, would be the diversified positions and combina- 

 tions of his satellites : their light must be faint, but yet of service ; and to 

 a traveller on the surface of this vast globe they must afford useful infor- 

 mation, as well with respect to time as to place. Our little earth must 

 probably be always invisible to a spectator situated on Jupiter, on account 

 of its apparent proximity to the sun, in the same manner as a planet at 

 half the distance of Mercury would be invisible to us. The year of Jupiter 

 must contain nearly ten thousand of his days, and that of Saturn almost 

 thirty thousand Saturnian days. Besides the vicissitudes of the seven 

 satellites revolving round Saturn, his ring must afford, in different parts of 

 his surface, very diversified appearances of magnificent luminous archer, 

 stretched across the heavens, especially in that hemisphere which is on the 

 same side of the ring with the sun. 



From the Georgian planet the sun must be seen but as a little star, not 

 one hundred and fiftieth part as bright as he appears to us. The axis of 

 this planet being probably near to the plane of its ecliptic, it must be 

 directed twice in the year towards the sun, and the limit of illumination 

 must approach to the equator, so that almost every place on his surface 

 must sometimes remain, for a great number of diurnal revolutions, in light 

 and in darkness ; the most moderate climates having one night, in their 

 long year, equal in duration at least to several of our years : and it must be 

 confessed that this planet would afford but a comfortless habitation to those 

 accustomed to our summer sunshine, even if it were possible to colonise it. 

 (Plate XXXIV. Fig. 501.) 



On the whole, we are tempted, from an almost irresistible analogy, to con-, 

 elude that the planets are all in some manner or other inhabited ; but at the 

 same time we can scarcely suppose that a single species of terrestrial animals 



