i88o.] The Evolution of Scientific Knowledge . 423 
A few of these may be noticed. When Lister, in 1683, 
proposed to the Royal Society that maps of the soils and 
minerals of England should be made, he probably was not 
aware of the existence of continuous layers of rock or strata. 
It was perhaps Hooke who first conceived the idea of 
“ raising a chronology ” out of the records of the rocks, while 
to Woodward has been attributed the earliest definite enun- 
ciation of the continuity of strata. We shall not therefore 
be far wrong in saying that, previously to the middle of the 
seventeenth century, the prevalent ideas of the structure of 
the earth’s crust were altogether general, disconnected, and 
indefinite. From such views have been evolved, by gradual 
stages, the special, connected, and definite conceptions of 
modern geologists ; for whatever may be said of geological 
theory, there can be no doubt that the tabulation of British 
strata may be thus chara( 5 terised. And it is only necessary 
to point to the recently-established connection between sedi- 
mentary, metamorphic, plutonic, and volcanic rocks, to 
show clearly the marked integration which has gone on in 
our knowledge of the crust of the earth. Nor do we find a 
different result when we turn from descriptive geology to 
causal geology. Although Ray, in 1692, “ enlarged upon 
the effects of running water upon the land, and of the 
encroachment of the sea upon the shores,” yet when Buffon, 
half a century later, maintained that “the waters of the 
sea have produced the mountains and valleys of the land,” 
his attempts at a natural explanation of the origin of the 
features of the earth were so far out of harmony with the 
accepted tenets of his age that he was politely requested, 
by the Faculty of Theology in Paris, to recant. When now 
we contrast the total ignorance of, or the wilful blindness 
to, the action of natural causes implied by this aCt, with the 
view generally accepted to-day, owing to the strenuous advo- 
cacy of Hutton and Lyell and their successors, that every 
feature of the earth’s surface, and every record buried in the 
rocks, is the result of causes similar in the main to those 
now in aCtion, — when we compare the views of Woodward 
or Whiston (dealing as they do with universal deluges and 
comet-tails) with the views of Ramsay or of Judd, we 
shall not fail to see a marked advance in all those special 
traits which characterise evolution. And now the broad 
generalisation that, with trifling exceptions, all geological 
aCtion is due to the antagonism of sun-heat and earth-heat 
shows an integration of knowledge that can scarcely be 
carried further. 
If now we turn from the history of our knowledge of the 
