PHYSICAL GEOLOGY. 191 



Delaire, Alexis. Le Fond des Mers; Etudes lithologiques. 

 Annales da Conservatoire. 



Fabri, B. [The Aqueduct of Narni, and its Works of Restoration.] 

 // Folitecnico, April, pp. 185-195. Abstract in Proc. Inst. Civ. 

 Eng. vol. xli. pp. 246, 247. 



Bicarbonate of lime is deposited in greater quantity the greater 

 the velocity of the water, and very little in stagnant water ; the depo- 

 sition rarely takes place except when w^ater is in contact with the 

 external air ; the deposit increases with the temperature and with the 

 distance from the source. W. T. 



Heming, W. T. On Segregation. Proc. Warwick Field Club 

 for 1874, pp. 38-54. 



Suggests that all banded c-alcareous members of systems may be con- 

 cluded to have segregated from deposits of calcareous mud. Objects to 

 the theory of the formation of coal by successive growths and sub- 

 sidences, and advocates that of the drifting out of vegetable matter 

 into deep water, when it sank, decomposed, and became consolidated. 

 Gives sections of the Shireoak Colliery, &c., to illustrate the thickness 

 of " earths " between coal-seams. Adduces the puri.ty of coal and the 

 wide extent of some seams as evidences against the theory of growth 

 and subsidence. W. W. 



Hunt, R. A contribution to the theory of Mineral Yeins. Trans. B. 

 Geol. Soc. Cornwall, vol. ix. part 1, pp. 22-25. 



After referring to the various theories concerning the origin of 

 mineral veins by deposition from vapours or solutions coming from be- 

 low, or solutions derived from the surrounding rocks, the author 

 directs attention to what he calls * surface force,' which is capable of 

 separating metals from their solutions. He supposes that this force 

 may have helped in the filling-up of metalliferous veins. C. L. N. F. 



Huxley, Prof. T. H. On some of the Results of the Expedition of 

 H.M.S. ' Challenger.' Contemporary Review, vol. xxv. pp. 639-660. 



After reviemng the information that had previously been obtained 

 as to the nature of the sea-bottom at great depths (chiefly in the 

 Arctic and Antarctic Regions), Prof. Huxley shows that the ' Chal- 

 lenger ' observations confirm the existence, in large quantities, of 

 Diatoms in the Antarctic seas and in the mud of the sea-bottom, which is 

 a fine siliceous powder, made up of diatomaccous plants and radiolarian 

 animals. "With respect to the Glohir/enna ooze of the zone between the 

 Arctic and Antarctic Regions, he now agrees with Prof. W. Thomson 

 that the Globujerince were essentially surface-animals, and that the 

 ooze is made up of their shells which had sunk to the bottom. In cer- 

 tain areas glauconite partially replaces the calcareous remains. Red 

 clay is now being formed at the greatest depths in a way different from 

 that of ordinary sedimentary deposit. Though not convinced that Prof. 

 Thomson's explanation of its origin (as the residue from the dis- 

 solving of the calcareous Glohigerina ehcUs) is the true one, ho believes 



