149 
OK THE PHYSICAL PROPERTIES OF ICE IN CONNECTION WITH 
THE GLACIAL PERIOD. BY W. M. WATTS, M.A., D.Sc. 
"When I found myself committed to read a paper before 
you to-day, I was in this difficulty, that I, not being a geolo- 
gist, had to address a Society of Geologists. Under these 
circumstances, it seemed to be all that I could do to select 
some subject, which, though not a geological subject, is of 
the utmost importance to geologists, in their attempts to 
unfold the past history of the globe ; and I thought it might 
be of interest to pass in review some of the properties of 
ice, to which, as a geological agent, very great effects are 
now attributed. The subject was suggested to me by a pas- 
sage in the address delivered by the late Professor Phillips 
to the Geological Section of the British Association at the 
Bradford meeting. 
Professor Phillips says : " One is almost frozen to silence 
in presence of the vast sheets of ice which some of my friends, 
(followers of Agassiz), believe themselves to have traced over 
the mountains and vales of a great part of the United King- 
dom, as well as over the kindred regions of Scandinavia. 
One shudders at the thought of the innumerable icebergs, 
with their loads of rock, which floated in the once deeper 
ITorth Sea, and above the hills of the three Hidings of York- 
shire, and lifted countless blocks of Silurian stone from 
lower levels, to rest on the precipitous limestones round the 
sources of the Kibble. 
"Those who, with Professor Ramsay, adopt the glacial hy- 
pothesis in its full extent, and are familiar with the descent of 
ice in Alpine valleys, where it grinds and polishes the hardest 
rocks, and winds like a slow river round projecting cliflEs, 
are easily conducted to the further thought, that such valleys 
have been excavated by such ice rubbers, and that even 
great lakes on the course of the rivers have been dug out 
