72 
THE GEOLOGIST. 
luminous bodies. The solar rays reaching the eartii lose some of their properties 
on radiatiutr from it — for it is well known all material substances not absorbing- 
heat arc radial in"" it, and by the aid of instruments of the most refmed character. 
Dr. Tyudall has^determined that such dark heat-rays pass ^Yithout loss through 
absolutely dry air— that they permeate many of the gases ; but their progress 
is arrested by the perfectly colourless and transparent olifiant gas. Amongst 
vapours the dark coloured bisulphate of carbon opposes no obstruction, but the 
attenuated vapour of ether stops them completely; while the vapour of water 
admits of their permeation with difficulty. Carbon-vapour in the air would 
facilitate the radiative action of the earth's surface, and occasion its rapid cooling, 
but water-vapour prevents the heat radiations from passing away, and preserves 
that temperature necessary for the existence of animals and plants. The warm 
gulf-stream, impmging on our coast, charges the air with moisture, and this 
envelope spreading over our island compels the heat absorbed from the sun by 
day to be retained in the earth at night, but if any circumstances produced a 
drier atmosphere we might suddenly find ourselves reduced to all the severities 
of an arctic climate. 
TMiat are the bearings of these new facts on the ancient geological condition 
of the Carboniferous age and the Glacial period, are questions at once suggested 
to our ♦^lind, for it appears to us tl at the presence of a large quantity of carbon- 
vapour in the atmosphere, as there has been generally supposed to have been 
in the Cod-era, would of itself have facilitated the radiation of heat from the earth's 
surface, and have promoted its rapid cooling ; but as besides this additional 
quantity of carbon, there is supposed to have been a vast amount of moisture in 
the air, we liave thus to consider what would be the effect of the commingled con- 
dition on the climatical state of the globe duiing that interesting and important 
era. The effect of a drier atmosphere in allowing the free radiation of heat is 
also, evidently, a point which cannot in future be left out of our speculations, on 
the causes of that extraordinary period of cold — the Glacial period. 
Geological Society oe London. — December 19, 1860. 
1. "On the Geological Structure of the South-west Highlands of Scotland." 
By T. r. Jamieson, Esq. 
2. " On the position of the beds of the Old Red Sandstone in the Counties 
of Forfar and Kincardme, Scotland." By the Rev. Hugh Mitchell. Com- 
municated by the Secretary. 
January^, 1861.— 1. "On the Distribution of the Corals in the Lias." 
By P. B. Brodie, M.A., F.G.S. 
2. " On the Sections of the Malvern and Ledbury Tunnels, on the Wor- 
cester and Hereford Railway, and the intervening Line of Railroad/' By the 
Rev. W. S. Symonds, A.M., F.G.S., and A. Lambert, Esq. 
NOTES AND QUERIES. 
Pterygotean Ova.— Where through the English range of the "Old Red" 
tilestones has Pterygotean ova {Parka decipiens, Page) been met with besides 
the Irmipley quarry, near Kiddermmster ?— George E. Roberts. 
Fossil Orangs.— Mr. R. W. Wallace in a most able paper on the Borneo orang, 
says :— " One cannot help reflecting on a former condition of this world which 
