72 



THE GEOLOGIST. 



luminous bodies. The solar rays reaching the eartJi lose some of their properties 

 on radiating from it — for it is well known all material substances not absorbing 

 heat are radiating it, and by the aid of instruments of the most refined character, 

 Dr. Tyndall has determined that such dark heat-rays pass without 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, impinging 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. 



What 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 "nind, 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 Coal-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 have thus to consider what would be the effect of the commingled con- 

 dition on the climatical state of the globe during 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. E. Jamieson, Esq. 



2. "On the position of the beds of the Old Red Sandstone in the Counties 

 of Forfar and Kincardine, Scotland." By the Rev. Hugh Mitchell. Com- 

 municated by the Secretary. 



January 9, 1861. — 1. "On the Distribution of the Corals in the Lias." 

 By P. B. Brodie, M.A., E.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.', E.G.S., and A. Lambert, Esq. 



NOTES AND QUERIES. 



Ptkuygotean Ova. — Where ihrough the English range of the "Old Red" 

 lilesiones has Pterygot can ova (Parka deci pirns, Page) been met with besides 

 the Trimpley quarry, near Kidderminster P — George E. Roberts. 



Fossil Orangs. Mr. K. W.Wallace inamosl able paper on the Borneo orangj 

 says : — " One cannot help reflecting on a former condition of this world which 



