22 CONSTITUENT MATERIALS OF THE EARTH 



like one of those vast sums in which astronomy deals so 

 largely, but which the mind altogether fails to grasp. 



The observation made upon the surface of the moon by 

 telescopes tends strongly to support the hypothesis as to all 

 the bodies of space being composed of similar matters subject 

 to certain variations. It does not appear that our satellite is 

 provided with an atmosphere of the kind found upon earth ; 

 neither is there any appearance of water upon the surface. 

 Yet that surface is, like the face of our globe, marked by 

 inequalities and the appearance of volcanic operations. 

 These inequalities and volcanic operations are upon a scale 

 far greater than any which now exist upon the earth's sur- 

 face. The mountains are, in many instances, equal in height 

 to nearly the highest of our Andes. They are generally of 

 extreme steepness, and sharp of outline, peculiarities which 

 might be looked for in a planet deficient in meteoric agen- 

 cies such as those which operate so powerfully in wearing 

 down ruggedness on the surface of our earth. The vol- 

 canic operations are on a stupendous scale. They are the 

 cause of the bright spots of the moon, while the want of 

 them is what distinguishes the duller portions, usually but 

 erroneously called seas. In some parts, bright volcanic matter, 

 besides covering one large patch, radiates out in long streams, 

 which appear studded with subordinate foci of the same kind 

 of energy. A large portion of the surface is covered with 

 circular eminences, called Ring Mountains, of various dia- 

 meters, from a quarter of a mile to several hundred miles, and 

 in some places as close together as the circles on the surface 

 of a boiling pot, which they in no small degree resemble. 

 Some even intrude upon and obliterate portions of the neigh- 

 bouring circles, thus leading to the idea of date, or a succes- 

 sion of events on the moon's surface. Generally, in the 

 centre, there is a mount, which appears to be connected, in 

 the way of cause, with the annular eminence, beyond which 

 again vast boulder-like masses are in some instances seen 

 scattered. What, however, most strikes the senses of an ob- 

 server, is the vast profundity of some of the pits between the 



