534 LICTURE XLir. 



in a second, which is only four times as great as that of a cannon ball : and 

 these stones, falling through the atmosphere, might very possibly generate so 

 much heat, by compressing the air, as to cause the appearance of fiery me- 

 teors, and to fall in a state of ignition. The appearance of the moon, as 

 viewed through a good telescope, is extremely well imitated by Mr. Russels 

 lunar globe, which is also capable of exhibiting, with great accuracy, the 

 changes produced by its librations. 



The climate of Mars is as much colder than ours, as that of Venus Is 

 warmer; in other respects there is no very striking difference: the inclina- 

 tion of his axis to his echptic being nearly the same as that of the earth's 

 axis, the changes of seasons must be nearly like our own. Dr. Herschel 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 surrounding 

 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 tne 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 tp 

 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, perhaps, fiom copious 

 atmospheres; and in this respect, as Avell 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 contem- 

 plated from Jupiter, would be the diversified positions and combinations of 

 his satellites; their light must be faint, but yet of service; and to a traveller 



