323 Prof. SilUman''s Address before the 



zed communities the most ample means of wealth and of un- 

 limited improvement. Geology, although not carried to perfec- 

 tion, is truly a science ; for — 



"Its ascertained facts are numerous ; they are correctly observed 

 and reported; they are skillfully classed and arranged, and a suffi- 

 cient number of general as well as particular conclusions, has 

 been drawn from them, to furnish the basis of a most interesting 

 science. Its boundaries are daily extending, and will be extend- 

 ed without limit by continued observations ; its evidence will 

 therefore constantly accumulate, and although its theoretical 

 speculations may change, nothing can occur to subvert the grand 

 conclusion that the earth has a regular structure, and that its ma- 

 terials have been arranged, under the operation of general laws 

 of great energy and duration, the physical expression of omnis- 

 cient intelligence and omnipotent sway, guided by benevolent 

 design, which becomes more and more apparent and convincing 

 with every new and successful research in geology."* 



OF ITS OBJECT, MEANS, AND ENDS. 



Geology discloses the structure of the earth, and the nature of 

 the mineral masses of which it is composed — the order of their 

 succession and arrangement — the chemical composition of the 

 rocks — the distinct minerals and the remains of organized beings 

 which they contain — the veins and beds of metals — the strata of 

 coal, limestone, plaster of Paris, mineral salt, clay, sand, and 

 other materials useful or indispensable to civilized society ; and 

 it investigates the proximate causes which have produced the 

 various effects that we behold, and which still continuing to ope- 

 rate will, in all future time, go on to produce their appropriate 

 results. 



It might seem to a common observer, that, treading only upon 

 the crust of the earth, we can know very little of the deep inte- 

 rior of a planet, whose diameter is eight thousand miles ; and that 

 therefore any attempt to ascertain its structure, must be equally 

 presumptuous and vain. But the geologist finds much more 

 ample sources of information than might at first appear. 



" Every artificial excavation — every well and cellar — every cut 

 for a fort, for a common road, a rail- way, or a canal — every stone- 



* The Author's Introduction to Mantell's Wonders of Geology. Am. edition. 



