484 Geological Society.—New Operation for Cataract. 
sometimes concreted: with which is also connected that . 
peculiar and valuable mineral known by the name of meuliere 
or burr-stone. In the Isle of Wight there is nothing to 
correspond with these important beds, except a thin layer of 
sand; but in the counties round London occurs in detached 
blocks a very pure siliceous sandstone, called the gray=. 
weatkers, which has been largely employed in architecture, 
and which is conjectured by Mr. Webster to be of cotem- 
porancous origin with the French sandstone. 
The upper fresh-water formation, one of the most re- 
markable and best characterized of any of the English beds 
above the blue clay, is best seen at Headen in the Isle of 
Wight. Its thickness is about 55 feet, and though not 
subdivided into distinct strata, it varies considerably in 
texture. Much of it consists of yellowish-white marl, more 
or less indurated, but friable and crumbling by frost. Many 
of the shells imbedded in this stratum are quite entire, con- 
sisting of various species of lvmnez, planorbes, helices, 
and other fresh-water shells. Over this bed is a stratum of 
clay with small bivalve shells, covered by a bed of yellow 
clay without shells, which latter is covered by a bed of 
friable calcareous sandstone, also without shells. To this 
succeed other calcareous strata with a few fresh-water shells, 
varying much in compactness from that of chalk to porcel= 
laneous limestone. \ 
This formation appears to have covered nearly all the 
northern half of the Isle of Wight. 
In the Paris basin are strata corresponding with these, 
both in their general composition and in the fossils which 
they contain, distinguished however by certain peculiar chas 
racters that are detailed by the author of this paper. 
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LXXIX. Intelligence and Miscellaneous Articles. 
NEW OPERATION FOR CATARACT. 
An experiment of the most important kind has recently 
been tried upon the pensioners of Greenwich Hospital, by 
direction of the honourable Governors of that Institution, 
with a view to ascertain the comparative success of the dif- 
ferent operations for cataract. The operation of extraction 
had been performed, it appears, upon the blind pensioners 
for the last twenty vears by the celebrated oculists the late 
Mr. Wathen, and his successur Mr. Phipps, but not, it 
is undersiood, with very satisfactory terminations. The 
Governors 
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