OF ORGANIC NATURE. 39 



from the nature of things, that that record should be 

 of the most fragmentary and imperfect character. 

 Unfortunately this circumstance has been constantl}' 

 forgotten. Men of science, like young colts in a fresh 

 pasture, are apt to be exhilarated on being turned 

 into a new field of inquiry, and to go off at a hand- 

 gallop, in total disregard of hedges and ditches, losing 

 sight of the real limitation of their inquiries, and 

 to forget the extreme imperfection of ■what is really 

 known. Geologists have imagined that they could tell 

 us what was going on at all parts of the earth's surface 

 during a given epoch ; they have talked of this deposit 

 being contemporaneous with that deposit, until, from 

 our little local histories of the changes at limited 

 spots of the earth's surface;, they have constructed a 

 universal history of the globe as full of wonders and 

 portents as any other story of antiquity. 



But what does this attempt to construct a universal 

 history of the globe imply? It implies that we shall 

 not only have a precise knowledge of the events which 

 have occurred at any particular point, but that we 

 shall be able to say what events, at any one spot, 

 took place at the same time with those at other spots. 



Let us see how far that is in the nature of things 

 practicable. Suppose that here I make a section of the 

 Lake of Killarney, and here the section of another 

 lake — that of Loch Lomond in Scotland for instance. 

 The rivers that flow into them are constantly carrying 

 down deposits of mud, and beds, or strata, are being as 

 constantly formed, one above the other, at the bottom 

 of those lakes. Now, there is not a shadow of doubt 

 that in these two lakes the upper beds are all older 



