SLATES. 319 



through the night of antiquity, and discern the forces 

 which have been in operation upon the earth's surface 



Ere the lion roared, 

 Or the eagle soared. 



From evidence of the most independent and 

 trustworthy character, we come to the conclusion 

 that these slaty masses have been subjected to enormous 

 pressure, and by the sure method of experiment we 

 have shown and this is the only really new point 

 which has been brought before you how the pressure 

 is sufficient to produce the cleavage. Expanding our 

 field of view, we find the self-same law, whose footsteps we 

 trace amid the crags of Wales and Cumberland, extend- 

 ing into the domain of the pastrycook and ironfounder ; 

 nay, a wheel cannot roll over the half-dried mud of our 

 streets without revealing to us more or less of the features 

 of this law. Let me say, in conclusion, that the spirit 

 in which this problem has been attacked by geologists, 

 indicates the dawning of a new day for their science. 

 The great intellects who have laboured at geology, and 

 who have raised it to its present pitch of grandeur, were 

 compelled to deal with the subject in mass ; they had 

 no time to look after details. Rut the desire for more 

 exact knowledge is increasing; facts are rlo,v : nj in 

 which, while they leave untouched the intrinsic wonders 

 of geology, are gradually supplanting by solid truths the 

 uncertain speculations which beset the subject in its in- 

 fancy. Geologists now aim to imitate, as far as possible, 

 the conditions of nature, and to produce her results ; 

 they are approaching more and more to the domain of 

 physics, and I trust the day will soon come when we 

 shall interlace our friendly arms across the common 

 boundary of our sciences, and pursue our respective taska 



