Royal Institution of Great Britain. 389 



The geological boundaries of this tract are, on the west and north- 

 west, the lias ; on the south-east and east, the Chalk-downs, extend- 

 ing from Salisbury Plain near Westbury to near Urchford, and thence 

 to Cherhill-liill on the east of Calne. ' The series of strata which it 

 includes, being the following, in a descending order. — 



Strata. Thickness. Strata. Thickness. 



Feet. Feet. 



Lower chalk Forest marble (continued) 



Chalk marl l.oO clay 10 



Upper green-sand 75 coarse oolite 25 



Gault 150 sandy clay and grit 10 



Lower green-sand 50 Bradford-clay .... 50 



Kimmeridge-clay 150? great oolite 140 



Upper calcareous grit .... 10 fullers-earth 150 



Coral rag 40 Inferior oolite 



clay 40 sandy oolite .. . 60 



calcareous grit ... . 50 sand and grit ... 70 



Oxford clay 300? — 130 



Kelloway rock 5 marlstone 10 



Cornbrash . . . .' 16 Lias ; upper marl 200 



Forest marble blue lias 50 



clay 15 white lias .... 10 



sand and grit .... 40 lower marl .... 20 



280? 



The surface of the country described in this paper is characterized 

 by three ranges of hills connected by two plains. — 1 . The most western 

 ridge is that of the great oolite, the highest part of which is 813 feet 

 above the sea. It is separated, by the plain of the Oxford clay, from 

 — 2. The range of the coral rag ; which again is detached, by the 

 valley and plain of the Kimmeridge-clay and gault, from — 3. The 

 range of Chalk-hills. 



The author describes in succession the several members of the se- 

 ries above mentioned : giving for each stratum an account of the 

 range and boundaries, a general type of the succession and propor- 

 tion of the component beds, with a detail of the physical characters 

 and local peculiarities and names, and an enumeration of the orga- 

 nized remains, detailing the species of the fossils, with their localities 

 and references to published figures. These copious details do not 

 admit of abridgement. 



The uaper is illustrated by the corresponding sheets of the Ordnance- 

 map, so far as they have been hitherto engraved, coloured geologi- 

 cally ; and by several sections explanatory of the succession of the 

 strata, and of the forms of the surface. 



FRIDAY-EVENINO PROCEEDINGS AT THE ROYAL INSTITUTION 

 or GREAT BRITAIN. 



March 27th.— On the Motion of Sap in I'lants ; by Mr. Burnett. 

 Mr. Burnett's principal objects were to develope and illustrate the 

 late researches of Dutrocheton Endosmose and Kxosmosc, or the de- 

 termination of currents of fluids through membranes, either in one 



direction 



