156 COSMOS. 



the solidification of its outer surface. New masses of rocks 

 are thus formed before our eyes, while the older ones are in 

 their turn converted into other forms by the greater or lesser 

 agency of Plutonic forces. Even where no disruption takes 

 place the crystalline molecules are displaced, combining to 

 Ibrm bodies of denser texture. The water presents structures 

 of a totally different nature, as, for instance, concretions of 

 animal and vegetable remains, of earthy, calcareous, or alumin- 

 ous precipitates, agglomerations of finely-pulverized mineral 

 bodies, covered with layers of the silicious shields of infusoria, 

 and with transpwted soils containing the bones of fossil ani- 

 mal forms of a more ancient world. The study of the strata 

 which are so differently formed and arranged before our eyes, 

 and of all that has been so variously dislocated, contorted, and 

 upheaved, by mutual compression and volcanic force, leads 

 the reflective observer, by simple analogies, to draw a com- 

 parison between the present and an age that has long passed. 

 It is by a combination of actual phenomena, by an ideal en- 

 largement of relations in space, and of the amount of active 

 forces, that we are able to advance into the long sought and 

 indefinitely anticipated domain of geognosy, which has only 

 within the last half century been based on the solid founda- 

 tion of scientific deduction. 



It has been acutely remarked, " that, notwithstanding our 

 continual employment of large telescopes, we are less ac- 

 quainted with the exterior than with the interior of other 

 planets, excepting, perhaps, our own satellite." They have 

 been weighed, and their volume measured ; and their mass 

 and density are becoming known with constantly-increasing 

 exactness ; thanks to the progress made in astronomical ob- 

 servation and calculation. Their physical character is, how- 

 ever, hidden in obscurity, for it is only in our own globe that 

 we can be brought in immediate contact with all the ele- 

 ments of organic and inorganic creation. The diversity of 

 the most heterogeneous substances, their admixtures and met- 

 amorphoses, and the ever-changing play of the forces called 

 into action, afford to the human mind both nourishment and 

 enjoyment, and open an immeasurable field of observation, 

 from which the intellectual activity of man derives a great 

 portion of its grandeur and power. The world of perceptive 

 phenomena is reflected in the depths of the ideal world, and 

 the richness of nature and the mass of all that admits of clas- 

 sification gradually become the objects of inductive reasoning. 



I would here allude to the advantage, of which I have al- 



