8 
power of eloquent description, and averse to the labour of reduc- 
ing his ideas to writing, few of his contemporaries would have 
dreamed of ranking William Smith as a man of genius : but pos- 
terity disregards externals, and judges men by their works ; and 
I reverentially believe that in the truest sense of the term he 
well deserves the name. His clear-sighted sagacity, foreseeing the 
immediate application of local observations to world-wide areas, 
arose from a high combination of observing, inductive, and 
speculative powers — a combination of which the highest scien- 
tific genius is composed ; his unswerving devotion, holding all 
other objects subservient to one great end, the heroic indiffer- 
ence with which he regarded all personal interests except in so 
far that they furthered it, his indomitable perseverance in the 
midst of difficulties and delays that hindered the production 
of his map of the English strata, all mark a man well worthy to 
be the first enunciator of a truth which in its consequences has 
opened to view a wide field for investigation that till his time lay 
utterly unapproachable. This grand and simple law, wedded to 
various branches of physical geology, already begins to “ embrace 
the whole surface of the globe.” This is what we are now doing. 
The “ after ages” have already begun, when, as he predicted, we 
shall “ get a tolerable description of the habitable world ;” and 
on the further progress of this work of identification of strata, 
of mapping and of section making, depends at present most of 
the advancement of correct geological theory. 
And here I would remark, that the results deducible from 
Smith’s discovery afford another pregnant example of the econo- 
mic application of purely theoretical principles, which in their 
first conception seemed but little connected with the furtherance 
of our material prosperity. In the expressive language of one 
of my colleagues, “ it is but the overflowings of science that thus 
enter into and animate industry” — a truth in the department of 
geology that I shall have occasion to illustrate in the sequel of 
this Lecture. 
The right understanding of the law of superposition is not of 
value only to the man of science : it is important to every 
speculator in mines, to every landed proprietor who cares to 
understand the mineral value of his property ; and the principles 
