ii.] THE PEBBLES' IN THE STREET. 59 



mysterious wanderers, of winch lie had seen many a 

 one about his native hills : 



As a huge stone is sometimes seen to lie 

 Couched on the bald top of an eminence, 

 Wonder to all who do the same espy 

 By what means it could thither come, and whence ; 

 So that it seems a thing endued with sense : 

 Like a sea-beast crawled forth, that on a shelf 

 Of rock or sand reposeth, there to sun itself. 



Yes ; but the next time you see such a stone, believe 

 that the wonder has been solved, and found to be, like 

 most wonders in Nature, more wonderful than we 

 guessed it to be. It is not a sea-beast which has 

 crawled forth, but an ice-beast which has been left 

 behind ; lifted up thither by the ice, as surely as the 

 famous Pierre-a-bot, forty feet in diameter, and 

 hundreds of boulders more, almost as large as cottages, 

 have been carried by ice from the distant Alps right 

 across the lake of Neufchatel, and stranded on the 

 slopes of the Jura, nine hundred feet above the lake.* 



Thus, I think, we have accounted for facts enough 

 to make it probable that Britain was once covered 

 partly by an ice-sheet, as Greenland is now, and partly, 

 perhaps, by an icy sea. But, to make assurance more 

 sure, let us look for new facts, and try whether our 

 ice-dream will account for them also. Let us investigate 

 our case as a good medical man does, by " verifying 

 his first induction." 



He says : At the first glance, I can see symptoms 

 a, ~b, c. It is therefore probable that my patient has 

 got complaint A. But if he has he ought to have 

 symptom d also. If I find that, my guess will be yet 



* See Lyell, "Antiquity of Man," p. 294 et seq. 



