BY R. M. JOHNSTON, F.LS. 143 
oceanic waters, within the limits determined already, by 
irregularities of the surface of the earth’s crust. 
A diversified distribution of the original surface magma of 
our globe is assumed with good reason by Mallet J. D. Dana,* 
Professor Hennessy, Archdeacon Pratt, Sir Archibald Geikie, 
and many other eminent physicists and geologists, as a 
primary condition ; and this primary condition, owing to the 
unequal rates of cooling, and differences of density of 
different masses of magma, is assumed to be the initial 
factors in producing elevated and depressed surfaces, includ- 
ing cup-shaped basins. The denudation of agencies such as 
the mobile gravitating force of water, only come into play at 
a subsequent stage, so that the older caused irregularities of 
surface, to a large extent, initiate and govern the direction 
and local intensities of subsequent denuding agencies. 
In accounting for the origin of Alpine lakes generally, by 
the Glacier Theory—-according to Ramsay’s view, which, 
during the first quarter of this year, has again been promi- 
nently brought before our notice by a discussion of the subject 
in the pages of Nature by Mr. T. G. Bonney,f the Duke of 
Argyle, { and Dr. Alfred Wallace § it would seem that the 
fascinations of Compte’s “ Law of the Simplest Hypothesis” 
have a dangerous tendency to promote a retrograde move- 
ment in geological science ; and that some of her most brilliant - 
exponents are not altogether mail-proof in resisting their 
fascinating influence when the charmingly disguised errors 
of simplicity of causation, by their aid, are championed in 
opposition to the truer, though, perhaps, less attractive 
complexity of variable or combined causes. In _ geological 
science, aS in economic science, there is ever a danger of 
mutilating a complex truth for the sake of erroneous sim- 
plicity ; and the bed of Procrustes was but a feeble engine of 
distortion or mutilation, as compared with all simple or 
specific hypotheses of causation specially devised to embrace 
somehow all effects, notwithstanding that the points of simi- 
larity in the latter may only appear to be of congeneric value, 
and not conspecific. 
Professor Marshall, in his recent work on “‘ The Principles 
of Economics” (Methods of Study) has given us earnest 
warning of this danger to all students of complex problems 
of science ; and has shown that the ‘‘ Physical sciences made 
slow progress so long as the brilliant but impatient Greek 
*The fact that the Continental and Oceanic areas were determined in the first 
cooling of the globe signifies that in the cooling or radiation of heat into space, 
there were areas of greatest and least contraction. This difference in cooling and 
the resulting level of the surface must have been owing to some difference of 
quality or condition in the material. (Dana’s ‘‘ Manual of Geology,” 3rd edition, 1879.) 
t Nature, p. 341 (Feb.). { Lbid., p. 369. § Ibid. (March) p. 437. 
