when, by publishing another volume (for which we all look with 

 earnest anticipation), he shall have recorded his discoveries in a 

 field of observation, almost his own ; he will then have reaped the 

 honour of being the first writer in our country to make known 

 a general system of " geological dynamics," — a new province 

 gained by the advance of modern science. 



But Mr. Lyell appears not only as the historian of the natural 

 world, but as the champion of a great leading doctrine of the Hut- 

 tonian hypothesis : and it is to the effects produced on the princi- 

 ples of his work by the latter character, that I now wish to call 

 your attention, with all the freedom belonging to fair discussion 

 and the love of truth. It would, indeed, be a strange anomaly in 

 the history of physics, if the Huttonian hypothesis, framed by its 

 distinguished author, without any knowledge of the most important 

 facts of secondary geology, should require no new adjustments, — 

 no limitation of its principles during the progress of discovery. 

 I cannot but regret, that from the very title-page of his work, 

 Mr. Lyell seems to stand forward as the defender of a theory. An 

 hypothesis is indeed (when we are all agreed in receiving it) an 

 admirable means of marshalling scattered facts together, and ex- 

 hibiting them in all the strength of combination. But by those who 

 differ from us, an hypothesis will ever be regarded with just sus- 

 picion ; for it too often becomes, even in spite of our best efforts, 

 like a false horizon in astronomy, and vitiates all the great results of 

 our observations, however varied, or many times repeated. 



It cannot, I think, be doubted, that in the general statement 

 of his results, Mr. Lyell has, unconsciously, been sometimes warped 

 by his hypothesis, and that, in the language of an advocate, he 

 sometimes forgets the character of an historian. In reading his 

 graphic and eloquent descriptions of the mighty works of degrada- 

 tion yearly going on through the eastern shores of England, or of 

 the enormous weight of solid matter hourly rolled down bv the 

 Ganges or the Missisippi, I have fancied that the earth was sliding 

 from under my feet, and that it would soon pass away, like the sand 

 of an hour-glass, beneath the waters of the ocean. 



But are there no antagonist powers in nature to oppose these 

 mighty ravages — no conservative principle to meet this vast de- 

 structive agency ? The forces of degradation very often of them- 

 selves produce their own limitation. The mountain torrent may 

 tear up the solid rock, and bear its fragments to the plain below : but 

 there its power is at an end, and the rolled fragments are left be- 

 hind to a new action of material elements. And what is true of a 

 single rock is true of a mountain chain ; and vast regions on the 

 surface of the earth, now only the monuments of spoliation and 

 waste, may hereafter rest secure under the defence of a thick vege- 

 table covering, and become a new scene of life and animation. 



It well deserves remark, that the destructive powers of nature 

 act only upon lines, while some of the grand principles of conserva- 

 tion act upon the whole surface of the land. By the processes of 

 vegetable life, an incalculable mass of solid matter is absorbed, 



