14 
POPULAR SCIENCE REVIEW. 
the chalk or mud washing down the slopes, and gradually 
wearing away the 66 everlasting hills.” The engineer may run 
his iron road under the strong cliff and on the lip of the 
ocean, saying to its liquid mass, “ Hitherto shalt thou come, 
and here shall thy proud waves be stayed ; ” but with the winter 
frost and in the winter storm the cliff falls and the waves beat 
on, turning dry land into sea ; while elsewhere the costly 
light-house, built also on the edge of the shore for a beacon to 
the mariner, in the course of years is left far inland by the 
receding waters. By this gradual redistribution of land and 
water, by gradual changes of elevation and depression, by the 
slow diversion of hot and cold currents, and by other causes 
likewise operating slowly, the temperature of the earth’s 
surface is diversified, not as a whole, but by gradual inter- 
change of climate between its several portions. Regions now 
temperate in other days have known the perennial glacier and 
the iceberg ; and the same regions now temperate, then glacial, 
at yet another time have reared in their warm enduring 
summers the grateful shade of palm-trees. The frozen North, 
treeless as it now is, once abounded in timber and foliage 
within a few degrees of the Pole. 
If, then, Sir Charles Bell could fairly argue that sudden 
changes in the inorganic matter of the globe, in the condition 
of the water, the atmosphere and temperature, pointed clearly 
to successive creations, not the gradual variation of species, may 
we not as fairly infer from the changes which are now proved 
to have been gradual instead of sudden that gradual variation 
of species is more likely to have prevailed than successive 
creation ? Certainly the teleologist cannot claim the point in 
favour of his argument from design if, while the outward con- 
ditions of life are constantly changing, species have been so 
stubbornly organised that they can make no change in corre- 
spondence. But emphatically he can claim the point in favour 
of his argument if he finds that not only have living organisms 
at any one period of the world’s history been admirably suited 
to the condition of the world at that period, but that living 
organisms have been so marvellously constituted that, as time 
rolls on. and climates change, and means of subsistence vary, 
and the whole face of the earth is altered, species too — which 
seem to shortlived and shortsighted observers rigidly fixed and 
unalterable — can adapt themselves by infinite variations to the 
ceaseless flow of circumstances. What is the adaptation of a 
few bones and muscles in the arm and hand for the advantage 
of a single animal, compared with this argument from the adap- 
tation of all the living species on the globe, not to a single set 
of conditions, but to a never-ending variety. 
Paley conceived the possibility of our planet revolving with- 
