1834.] European Science. 355 



The telescopic appearance of the moon, the snowy covering of her Phlegrsen 

 continents, and the silent ruggedness of her frozen seas, might suffice to disprove 

 the existence of a temperature upon her surface equal or similar to that of the 

 earth. In what respect, it may be asked, differs the aspect of the bright portion 

 of the moon's disc from that which would be assumed by a poition of the Hima- 

 laya mountains viewed at the distance of the moon, when winter has clothed both 

 eminence and valley in a uniform robe of snow, and bound in icy chains every 

 stream and expanse of water ? In that elevated region of the earth there is a par- 

 tial, in the moon there is nearly a total, want of that atmospheric envelope, which, 

 like a garment, enables those bodies which receive it to retain the solar warmth. 

 The moon's rays will no more heat a warmer thermometer than will the concentrated 

 light given out by a snowy range of terrestrial mountains. This refrigeration 

 appears to have extended through a great thickness of the moon's external crust, 

 for her volcanoes are nearly extinct : the flames which they give out were barely 

 visible even through Sir W. Herschel's powerful telescopes. 



Still less compatible with their snowy whiteness, and with the bold precipices 

 and overhanging character of the lunar Alps, is Sir John Herschel's idea of a 

 monthly revolution of the climate on the moon's surface. Not onlywouldthe linea 

 terminator or boundary of light and darkness be followed during the moon's increase by 

 a bright line of melting snow, while the enlightened face generally would present a 

 scene of overwhelming deluges, breaking down the edges of its numerous elevated 

 cavities, and reducing the moon's surface to a near resemblance to that of the earth ; 

 but the irresistible expansive force of the ice, monthly freezing in the fissures and 

 cavities of its mountains, would in the course of a few years reduce these to a much 

 smaller altitude than those which are now left upon the earth. 



It is probable indeed, that the causes of the striking differences between the 

 lunar and terrestial surfaces may be referred solely to the smaller bulk and rarer 

 atmosphere, of the moon. An attentive examination of the most ancient cra- 

 ters of volcanoes now active, such as Vesuvius, will shew, that the first stage of 

 a violent eruption must have been the blowing into the air an inverted conical 

 mass of the mountain, two, three, or four miles in diameter, leaving a crater of 

 similar dimensions, such as may yet be traced of Vesuvius, where Monte Somma 

 forms the eastern edge of the ancient crater, upwards of four miles distant from 

 the western, with the modern cone and crater rising between them, like the central 

 elevations, which are to be seen in the circular hollows of the moon. From the 

 smaller force of gravity at the moon's surface, the masses displaced by those ex- 

 plosions have greatly exceeded the size of any craters that can now be traced upon 

 theearth, many of the lunar cavities being from twenty to fifty miles in diameter and 

 a mile or two iu depth. A rapid refrigeration appears to have followed the active 

 era of the lunar volcanoes, so that the whole of them remain visible and unaltered 

 by falls of rain or by alternate frosts and thaws, (while the operation of these causes 

 upon the earth's surface has left barely traceable vestiges of whole volcanic re- 

 gions ;) and, during the short period of her being a habitable world, her atmos- 

 phere must have consisted ch iefly of watery vapour. 



If would appear, from the known laws of the communication of heat by radiation, 

 that the created universe is constantly suffering a loss of that principle, which 

 can be supplied only by successive exertions of the creating power. Hence the 

 decay and loss of old stars, and the appearance of new ones recorded in the annate 

 of astronomy. 



