386 Scientific Intelligence — Geology. 



piers of the Bridge of Caligula, giving the same amount of subsidence, 

 yearly. There were, besides, many similar proofs in the partly sub- 

 merged houses and causeways of Puzzuoli. The perforations of the 

 Pholades in the columns indicate a former period, during which the 

 temple remained submerged at a stationary level ; and contempo- 

 rary accounts state, that, by an instantaneous movement, it was 

 lifted to some height above the sea, which receded nearly 200 paces, 

 leaving an immense quantity of fish, which were collected by the in- 

 habitants. This took place in October 1538, immediately before the 

 elevation of Monte Nuovo. 



26. Disicovery of a large Deposit of Black Bituminous Coal 

 in Chatham Island, one of the Galapagos. — About the middle of 

 the valley my attention was attracted to the foot of one of the 

 hills, where the earth had fallen down, and left exposed to view 

 large black rocks. I went over and examined it, and found them 

 to consist of coal in large quantities, and extending away under the 

 hills. As I was fatigued, I prepared my encampment for the night, 

 and my meal, and which, to test my discovery, I cooked on a 

 wooden spit, before a fine fire of coal; it quickly ignited, flamed 

 up, and burned after the cheerful manner of Cannel coal. I was 

 greatly pleased with this useful discovery. There were great hills 

 of it, and an immense supply could be here obtained, if there was a 

 sufficient arrangement to convey it to the sea-side. — {Adventures 

 in the Pacific. By John Coulter, 3I.B., p. 107.*) 



27. Air of Mines. {Vlnstitut, No. 603, 1845, p. 255.)— M. 

 Leblanc, on analysing the air of PouUavuen mine, finds that when 

 most altered by respiration and combustion of lamps, there is 3 to 

 4 per cent, of carbonic acid, and a diminution of 4 to 5 per cent, in 

 the proportion of oxygen. The miners' lamps are extinguished ; 

 but by placing the meshes of two lamps in contact, combustion often 

 goes on where one alone fails. The respiration of the miners is a 

 little impeded, but work is possible when this limit is not exceeded, 

 provided the temperature is low. Air collected at Huelgoet, in an 

 unoccupied shaft, shewed a diminution of 10 per cent, in the amount 

 of oxygen, without a replacement of the same by carbonic acid, which 

 circumstance he attributes to the influence of decomposing pyrites.— 

 (American Journal of Science and Arts, Vol. i., 2d Series, No. 1, 

 p. 118.) 



28. The Oust- Art, and shores of Lake Aral. (V Institute 605, 

 p. 256.) — This region, hitherto little known, has been geologically 

 examined by M. S. de Helmersen. He has ascertained, that at the 

 period when the beds of the Oust-Art were deposited, the Caspian 

 and Aral seas formed a single Mediterranean sea ; that at the middle 

 of this sea stood a high island — the Oust-Art — at whose foot com- 



* This fact we consider of importance, as connected with the pxopositioii of 

 steaming across the Pacific Ocean. 



