THE GEOLOGIST. 
JUNE 1863. 
EIPPLE-DRIFT IN MICA-SCHIST. 
Br THE Editor. 
Of all English geologists, Mr. Sorbj has been at once tlie most 
indefatigable and the most successful in the study of the microscopic 
structure and metamorphic conditions of rocks. The brief abstract 
furnished us by the Geological Society, which we print at p. 231, 
gives but little idea of the importance of the paper Mr. Sorby read 
last month. It gives, it is true, the pith of the subject, but so 
short and inexplanatory a paragraph is not likely to attract such at- 
tention as the paper deserves. Those who have tlie pleasure of Mr. 
Sorby's acquaintance know how persistently he works at anything 
puzzling which comes in his way. He never leaves it until he has 
got to the solution of the riddle. It happened some time ago, when 
in Germany, at the meeting of savants at Speyer, on which occa- 
sion he transmitted an account of the proceedings, with some notes 
on meteorites and sponges (see Vol. lY. p. 501), that Professor 
Blum presented him with a specimen of the singular conglomerate 
known as the " nagel-flue." This conglomerate, which occurs in 
some places in Switzerland, consists of hard limestone pebbles, 
the ends of some being impressed into the substance of others, — 
a condition hitherto inexplicable, although Blum, Yon Dechen, 
Escher von der Linth, Noggerath, Daubree, and others have essayed 
opinions and suggestions, some of them attributing the impressions 
to merely mechanical, others to purely chemical action. In working 
out this investigation, Mr. Sorby eliminated evidence of a new 
phase in the correlation of physical forces ; and in an able and 
VOL. TI. 2 D 
