Geological Society. 301 



with these lofty speculations, in which man seems to be no longer 

 a worshiper at the portal of Nature's temple, but is allowed to pass 

 within, and to be so far a partaker of her mysteries, as to see with 

 his intellectual eye both the past and the future. 



I believe that the law of gravitation, the laws of atomic affinity, 

 and, in a word, all the primary modes of material action, are as 

 immutable as the attributes of that Being from whose will they 

 derive their only energy. But it is not merely through the simple 

 and unchangeable modes of material action, or through the simple 

 laws by which the parts of material things are bound together, that 

 the works of nature are submitted to our senses. The things 

 we see on the surface of the earth are in a continual state of move- 

 ment and change, of destruction and renovation. They are not 

 merely subject to those fundamental powers, commonly considered 

 as the laws of nature ; but the very powers themselves act under 

 such endless modifications, sometimes combined together, and some- 

 times in conflict, that there follow from them results of indefinite 

 complexity, the very simplest of which are removed far out of the 

 reach of any rigid calculation. 



As the primary laws of matter are immutable, every physical ex- 

 periment tried under the same conditions must end in the same 

 results, whether they be chemical, or mechanical, or a compound of 

 both. But let any new and unknown condition be introduced, and 

 the results are not only changed, but are often the very contrary of 

 what we should have at first anticipated. Let it again be con- 

 sidered within what narrow limits we have the power of modify- 

 ing the conditions of any physical experiment, and how little we 

 still know of those mysterious imponderable agents which co-exist 

 perhaps, with gravitation, and unquestionably play their part in 

 every change and every combination and we must see the utter 

 hopelessness of bringing under the definite calculations of any me- 

 chanical law, those mighty combinations still going on in the great 

 laboratory of nature. 



Of the origin of volcanic forces we know nothing : but we do 

 know that they are the irregular secondary results of great masses 

 of matter obeying the primary laws of atomic action that they 

 differ in their intensity are interrupted in their periods and are 

 aggravated or constrained by an endless number of causes, external 

 and purely mechanical. Of all modes of material combination, 

 those of which I now speak are perhaps the most complicated. 

 To assume, then, that volcanic forces have not only been called 

 into action at all times in the natural history of the earth, but also, 

 that in each period they have acted with equal intensity, seems to 

 me a merely gratuitous hypothesis, unfounded on any of the great 

 analogies of nature, and I believe also unsupported by the direct 

 evidence of fact. This theory confounds the immutable and pri- 

 mary laws of matter with the mutable results arising from their 

 irregular combination. It assumes, that in the laboratory of nature, 

 no elements have ever been brought together which we ourselves 

 have not seen combined $ that no forces have been developed by their 

 combination, of which we have not witnessed the effects. And what is 



this 



