V.—GEHEOLOGY. 
Arr. LI.—Volcanie Action regarded as due to the Retardation of the Earth’s 
Rotation. By Joun Carrutuers, M. Inst. C.E., Engineer in Chief to 
the New Zealand Government. 
[Read before the Wellington Philosophical Society, 21st August, 1875.] 
Voucanic Action is so impressive in all its manifestations that it is difficult 
to realise (what, nevertheless, is true) that the mechanical energy required 
to produce it is much less than that displayed by the more uniformly acting 
powers of nature. If, for instance, the whole energy of the tides were 
converted into volcanic action, it would, in a short time, cover the face of 
the globe with mountains higher than the Alps or Andes, and render the 
earth as mountainous as the moon, where, if the hypothesis I now bring 
forward is correct, much actual motion has been converted into volcanic 
action, which with us, has not yet been so converted, but still remains in — 
the form of actual motion of rotation. 
The power which has raised and still maintains our hills and continents 
above the sea is, I believe, derived from the retardation of the earth’s rota- 
tion. 
It is quite certain that the earth does revolve less quickly than it used 
to do, owing to the friction of the tides against the bottom of the ocean, 
and it has been calculated that on this account the day is longer by one 
second than it was about a hundred and seventy thousand years ago. 
Motion cannot be destroyed, and, therefore, that which the earth has lost 
has taken some other form. The greater part of it has passed insensibly 
away as heat, having, after first slightly warming the earth, been radiated 
into space. Even the small part, which by my hypothesis, becomes volcanic 
action, would also pass insensibly away if it were not accumulated, as a 
weak stream of electricity is accumulated in a Leyden jar until sufficient 
intensity had been obtained to make its effects sensible. The strength and 
rigidity of the earth’s crust act the part of this volcanic Leyden jar. 
There is, we know, a tide in the ocean due to the attraction of the sun 
and moon on the parts of the earth nearest to them, being greater than on 
the parts more remote. There is also a tide in the solid crust of the earth 
from the same cause, although the rigidity of the latter makes it one of 
strains rather than of movements. Still, it is contrary to all our know- 
ledge of matter to suppose that there is absolutely no movement, for matter 
