382 Transactions.—Geology. 
Let us think over the matter. To produce a dense atmosphere from 
interior heat, it seems to me that we must go the length of supposing the 
waters of the ocean to be raised to the boiling point. Unless raised to that 
point, I do not see that the evaporation would be much greater than at 
present. Then, with the water at the boiling point, how are we to manage 
enough cold for precipitation ? 
With water at the boiling point, how are we to account for the existence 
of the corals, of the crustaceans, of the molluscs, etc., of the coal measures? 
how account for the similar organisms, including fish, of the old red sand- 
stone and of the silurian rocks? These old molluscs and fish may have 
been good eating when boiled, but could not very well live and reproduce 
their species in boiling water. 
Again, with the ocean at the boiling point, what would be the effect of 
the internal heat on the land? I would suggest that it would be to deprive 
the surface of moisture, which would be driven off in a state of steam, and 
would therefore render it unfit to support vegetation, instead of, as is sup- 
posed, to maintain that of a rank and luxuriant nature. A moderate in- 
crease of external heat, that is to say, of heat derived from the sun, would 
produce great changes, whether favourable to the production of a dense 
vegetation or not, might depend upon circumstances, but a vast increase of 
internal heat must be assumed to make any perceptible change in the 
climate as regards the growth of plants. 
I may, however, be combating a shadow, because we have only to refer 
to Lyell to find an opinion of primary authority as to the origin of coal. 
He states as follows—‘‘So long as the botanist taught that a tropical 
climate was implied by the carboniferous flora, geologists might well be at a 
loss to reconcile the preservation of so much vegetable matter with a high 
temperature, for heat hastens the decomposition of fallen leaves and trunks 
of trees, whether in the atmosphere or in water. It is well known 
that peat, so abundant in the bogs of high latitudes, ceases to grow in the 
swamps of warmer regions. It seems, however, to have become a more 
and more received opinion that the coal plants do not on the whole indicate 
a climate resembling that now enjoyed in the equatorial zone. The ferns 
range as far as the southern part of New Zealand, and Araucaria pines 
occur in Norfolk Island. A great predominence of ferns and lycopodians 
indicate moisture, equability of temperature, and freedom from frost, 
rather than intense heat, and we know too little of the segillarie, calamites, 
asterophyllites, and other peculiar forms of the carboniferous period to be 
able to speculate with confidence on the kind of climate they may have 
required,” 
