Geological Society. 299 



The form put on by a fluid body in rotation is an abstract ques- 

 tion, which might or might not have any real application to the 

 bodies of our solar system. But direct geodesic observations, as 

 well as the relative position of land and water, prove that the stra- 

 tified matter on the crust of the earth is deposited in near confor- 

 mity to the surface of a true spheroid of rotation. Here then we 

 have, in spite of one of the arbitrary dogmas of the Huttonian 

 theory, an indication of a primeval fluidity before the commence- 

 ment of any one phenomenon coming within the direct specu- 

 lations of geology. And again, the direct phenomena of geology 

 are in the strictest harmony with this conclusion. For, after passing 

 through a few stages of stratified matter, formed by the degradation 

 of matter in a prior state of solidity, we are conducted to other un- 

 stratified masses with that crystalline structure which implies an 

 anterior fluidity in some cases unequivocally, and in all cases pro- 

 bably, derived from the solvent power of heat. 



But if the earth ever existed in any state approaching to igne- 

 ous fusion, it must have undergone a great diminution of tem- 

 perature before it was fitted for the habitation of any organized 

 being. And here again geological facts are at least in a general 

 accordance with the hypothesis ; for the forms of the living beings 

 entombed among the ancient strata, not only seem to indicate a 

 high temperature, but also a gradual refrigeration of the surface of 

 the earth 



Here however we meet with an unexpected difficulty. If during 

 any period the earth have undergone a sensible refrigeration, it 

 must also have undergone a contraction of its dimensions; and also, 

 as a necessary consequence of a well known mechanical law, an ac- 

 celeration round its axis of rotation. But direct astronomical ob- 

 servations prove that there has been no sensible diurnal acceleration 

 during the last 2000 years ; and therefore, by inverting the steps of 

 the reasoning, we prove that during that long period there has been 

 no sensible diminution in the mean temperature of the earth. This 

 difficulty does not, however, entirely upset the previous hypothesis: 

 it only proves that the earth had reached an equilibrium of mean 

 temperature before the commencement of good astronomical ob- 

 servations. 



But if, Gentlemen, our speculations are thus limited and guided 

 by the observations of astronomy, we have in part paid back to that 

 exalted science the obligations we owe to it. The great bodies 

 of our system leave behind them no marks to track their pro- 

 gress through the heavens ; and the vast secular periods we can 

 calculate, reaching to ages long anterior to the records of our 

 being, might be mere fictions of the mind which have never had any 

 archetype in nature. But in the phenomena of geology we are 

 carried back, almost at our first step, into times unlimited by any 

 narrow measures of our own; and we exhibit and arrange the monu- 

 ments of former revolutions requiring for their accomplishment per- 

 haps all the secular periods of astronomy. Nor is this all. We show- 

 by help of records, not to be misinterpreted, that during this vast 



2 Q 2 lapse 



