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wells, in the gravel and London clay in Essex, showing that water 
occurs under the London clay at various depths; the deepest at 
Foulness Island, being 460 feet. He attributes this inequality in 
part to unevenness in the surface of the subjacent chalk. On 
reaching the chalk a large volume of water usually rushes up. Ar- 
tesian wells are now general in Essex, where they are of the greatest 
utility in districts that have no natural springs. He also gives an in- 
teresting list of localities, both of constant and intermitting springs, 
some of them very powerful, that burst out from the chalk. 
Dr. Mitchell has also communicated an account of deleterious 
gases that occur in wells in the chalk and strata above it near Lon- 
don. The most abundant of these, namely, carbonic acid gas, issues 
very partially and only from certain strata, and produces sometimes 
effects fatal to persons employed in digging wells. Sulphuretted 
hydrogen is occasionally met with in chalk ; and both sulphuretted 
hydrogen and carburetted hydrogen occur in beds immediately above 
the chalk. 
SUPERCRETACEOUS FORMATIONS. 
In illustration of the history of the Eocene division of the tertiary 
strata, Mr. Bowerbank has concluded, from his personal observations 
at White cliff bay in the Isle of Wight, that there are no well-defined 
zoological distinctions between the London and plastic clays, but that 
in the cliffs of this bay the same shells are common to alternations 
of these clays with one another. At Alum bay also he found many 
London clay fossils in beds of greenish grey sand and clay below 
the variegated sands and clays referred by Mr. Webster to the pla- 
stic clay. A similar rectification was sometime ago proposed by 
Professor Sedgwick. 
We have also witnessed during the past year the commencement 
of a valuable publication by Mr. Bowerbank on the fossil fruits and 
seeds of the London clay, illustrated with very numerous and accu- 
rate engravings by Mr. James Sowerby. 
The great attention the author has long paid to the remains of fruits 
and seeds which occur in such vast abundance in the Isle of Sheppy, 
whence he has collected not less than 25,000 specimens, place him 
in a position peculiarly advantageous for the object before him. 
In this work drawings will be given of the anatomical structure of 
