08 Geological Society: — 



rations, with Hours and Reduction of Observations, the latter 

 treating \erv Fully of the most recent and exact methods employed. 

 In the " Notes on Registration" and " Kules for Observers" the 

 amateur will find much important information. 



The second part of the Vade Mecum is a very valuable produc- 

 tion : the portions of greater interest treat of the physical properties 

 of air and vapour and the physical geography of India ; the peculiar 

 conformation of the surface of India, which, is lucidly described, 

 renders the country in relation to Meteorology an epitome of atmo- 

 spheric physics. Students will derive much useful information from 

 their conjoint study. The succeeding portions, on Temperature, 

 Pressure, Wind and Bain, are full of important information; and 

 the concluding part, on Storms, contains the most recent develop- 

 ment of the Theory of Cyclones, especially the incurvature of the 

 wind's motion in storms. 



X. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from p. 473.] 



March 20, 1878.— Henry Clifton Sorby, Esq., E.ft.S., President, 



in the Chair. 



rpHE following communications were read: — 



-*- 1. " On the Chronological Yalue of the Triassic Strata of the 



South-western Counties." By ^Y. A. E. TTssher, Esq., P.G.S. 



The author maintained that the general thinning-out of the Trias 

 in the South-Devon and West-Somerset area as it is traced north- 

 ward, of which he adduced evidence, proves that this area was not 

 connected with that of Gloucestershire and the midland counties 

 until the later stages of the Keuper ; and endeavoured to show by a 

 comparison of sections that the area east of Taunton and south of 

 the Mendips was not submerged before the deposition of the Lower 

 Keuper Sandstone, and probably not until the later stages of its 

 formation, the Quantocks acting as a barrier dividing the Bridge- 

 water area from the Watchet valley. He thought that a subsidence 

 progressing from south to north led to earlier deposition in South 

 Devon, and to a consequent attenuation of the lower beds towards 

 Watchet and Porlock. Hence the lowermost beds of the Trias of 

 the south coast are much thicker than their more northerly equi- 

 valents, and probably were still thicker where the English Channel 

 now flows, some beds perhaps dating as far back as Permian times. 

 The presence of numerous fragments of igneous rocks (quartz- 

 porphyries) in the basement-beds of the South-Devon Trias, and 

 the absence of known corresponding rocks in the county, led the 

 author to infer that the cliffs and beds of the early Triassic sea were 

 composed of such rocks, any undestroyed portions of which would 

 probably occur either under the Triassic beds near Dartmoor and 

 between Xewton and Seaton ; or in the area now occupied by the 



