PHYSICAL GEOLOGY. 165 



HiLGARD, EuG. W. On some Points in Mallet's Theorj' of Tul- 



canicity. Amer. Journ. ser. 3, vol. vii. pp. 535-540 ; and Phil. 



Mag. ser. 4, vol. xlviii. pp. 41-53. 



Review of Mr. Mallet's paper, in Phil. Trans, vol. clxiii. p. 147 



(1873). On the whole, favourable to his views. Discusses the 



Pacific coast fissure-eruptions and Prof. Le Conte's theories thereon. 



0. A. L. 



HiRSCHWALD, J. IJeber die Umwandlung verstiirzter Gruben-Zim- 

 merung in Braunkohle aus dcm " alten Mann " der Grube Dorothco 

 auf dem Oberharz. [Conversion of timber into Brown Coal, as 

 seen in the ancient workings of the Dorothy Mine in the Upper 

 Hartz.] Yerh. k.-k. geol. Keichs. pp. 14, 15. 

 Describes a visit to the mine, the drifts of which had cut through 

 certain old workings, filled up with masses of clay-slate, along with the. 

 original timbering. The timbers had been partially converted into a 

 regular brown coal, apparently as the result of their permeation by 

 water with mineral matter in solution, whilst at the same time sub- 

 jected to a high temperature, comparatively speaking, and a very con- 

 siderable amount of pressure from the superincumbent rock. H. A. N. 



Ho WORTH, Henry H. Recent Elevations of the Earth's Surface in 

 the Northern Circumpolar Regions. Journ. Roy. Geogr. Hoc. 

 vol. xliii. pp. 240-263. 



The author's conclusions arc : — '' that the great mass of land that 

 surrounds the North Pole .... is undergoing a general movement 

 of upheaval .... and in those areas which are accessible enough 

 to enable us to experiment, as in Scandinavia &:c., we find that the 

 movement is going on now at a greater or less rate. This general 

 movement of Circumpolar land having its focus apparently near the 

 Pole, has no doubt been coincident with a corresponding revolution 

 in other physical phenomena, such as climate, the distribution of 

 magnetism," &c G. A. I . 



Hfnt, Dr. T. S. The metamorphism of Rocks. Proc. Amer. Assoc, 

 vol. xxii. B. pp. 115, 116 (abstract). 



HcTTON, Capt. C. E. A criticism upon the Contractional Hypothesis. 

 Amer. Journ. ser. 3, vol. viii. pp. 113-123. 



Concludes that the greatest possible contraction due to secular 

 cooling is insufficient to account for the phenomena attributed to it by 

 the contractional hypothesis. Suggests that if we were to assign 

 30 miles as the diminution of the earth's mean radius since the fonna- 

 tion of a cooled exterior, we should probably reach the utmost limit 

 consistent with Fourier's theorem. By far the larger portion of this 

 contraction must have taken place before the commencement of tlio 

 Paleozoic age; by far the larger portion of the residue must have 

 occurred before the beginning of the Tertiary ; and yet the whole of 

 this contraction would not be sufficient to account for the disturbances 

 which have occurred since the close of the Cretaceous. E. B. T. 



