158 
4,765 feet high, or nearly a mile, before the melting-point 
sank to the temperature of the ice and any motion of the ice 
could take place. 
The theory of the ice-sheet, as generally stated, assumes, 
1 believe, the epoch to have been one of intense cold. It has 
been pointed out previously that extensive ice deposits do not 
indicate merely a time of great cold, but rather a time when 
there were greater contrasts of temperature on the earth than 
now, — great heat being just as necessary for the production of 
aqueous vapour as cold for its rapid condensation into snow. 
And now a consideration of the physical properties of ice 
seems to show that if the climate were one of intense cold, the 
ice deposits when formed would not move down their valleys, 
at least not in the same way as glaciers do now-a-days. 
Experiments on the bending of ice planks by their own 
weight, put in a clear light the great plasticity of ice at 
the melting point, and its rigiditj^ at low temperatures. Mr. 
Matthews found that a plank of ice 6 feet long and 2| inches 
thick, supported by its ends, bent in the middle 7 inches in 
7 hours ; during a thaw, when the temperature was 30° F. 
only IJ inches in 24 hours. 
Another plank of about the same length, but only 1|- 
inches thick, bent If inches in 22 hours, at a temperature 
of 26° F. 
Similiar results were obtained by Taff, who found that a 
bar of ice 18 inches long, 1 inch wide, and J inch thick, bent 
2 or 3 m. m. in 24 hours when the temperature was several 
degrees below zero, but when the temperature rose to nearly 
the freezing point the bending amounted to 9 m. m. in 24 
hours. 
Professor Phillips concludes, from Canon Moseley's experi- 
ments, that no glacier of greater depth than 1,000 ft. could 
exist. If I understand the recent observations of Geologists 
aright, there is evidence that the present Irish Sea was 
