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during the last glacier epoch most of these hollows were again 
filled with ice to a great height, but these last glaciers were 
comparatively small. 
Mr Kingsley especially dwelt upon the difficulty of dis- 
entangling the scattered moraine from the drift, and also of 
distinguishing between the striations belonging to the two cold 
epochs. 
Professor HUGHES, in a discussion with Mr Kingsley, ex- 
plained and defended Professor Ramsay’s theory of the glacial 
erosion of lake basins, but was not prepared to go so far as that 
author in his application of it. He said we wanted some more 
definite information as to the shearing force of ice: there was a 
limit to the possible depth to which ice could descend and pass 
out without being embayed. The observations in “roche mou- 
tonnée,” where the surrounding ice corresponded to the sides of 
the rock-basin, shewed that ice could descend to a considerable 
depth without being embayed; and it had to be shewn in each 
separate case whether it was possible or probable that ice had 
scooped out, or been embayed in, any particular clepression. 
He did not think there was evidence to shew that glacial con- 
ditions were synchronous in the Northern and Southern hemi- 
spheres, or even in Europe and America. 
Mr Hin described a method by which a “camera obscura” 
may be employed to fix the position of the boat taking sound- 
ings. 
Professor MAXWELL stated that piano-wire furnished the 
best means of suspending the sounding-plummet. He men- 
tioned some other improvements in the methods used for 
taking soundings. ; 
Mr Bonney said that the facts collected by Mr Kingsley 
were very valuable, because the need of careful and accurate 
soundings was so much felt in discussions as to the origin of 
lake-basins. He was himself of opinion that the erosive force 
of glaciers was but small, and that they had not excavated such 
