GENERAL SUMMARY. 
259 
had not been previously pointed out, and indeed an 
objection, to which for long I saw no answer, was 
suggested to me by Mr. Francis Galton. He urged 
that no accumulation of water in the northern 
hemisphere would give promontories pointing to the 
north. I tried various hypothetical enlargements of 
the northern seas, but in vain. The explanation lies, 
I think, in the necessary equivalence of the great 
folds on the Earth’s surface,^ 
If folded mountains are due, as above suggested, 
to a diminution of the diameter of the Earth, every 
great circle must have participated equally in the 
contraction. The east and west folds would on the 
whole counterbalance to those from north to south. 
This must be so theoretically, but we have no means 
of testing it by exact figures. It is interesting, how- 
ever, to observe that while the mountain chains of 
the Old World run approximately from east to west, 
those of America are in the main north and south. 
Speaking roughly, the one series would seem to 
balance the other, and we thus get a clue to the re- 
markable contrast presented by the two hemispheres. 
Again, in the northern hemisphere we have chains of 
mountains running east and west — the Pyrenees, Alps, 
Carpathians, Himalayas, etc. — while in the southern 
hemisphere the great chains run north to south — the 
17* 
