230 SIR HENRY H. HOWORTH^ D.C.L.^ F.R.S., ON ICE OR WATER. 



surface level in some very distant places. We must remember that 

 at this present time the temperature of England is above the 

 ordinary temperature of other countries in the same latitude. We 

 are warmed by the Gulf Stream ; we are warmer than we should be 

 if the Gulf Stream did not come our way. 



There have been a great many causes but there is abundant 

 evidence to show there was an enormously increased amount of ice 

 at the period of which Professor Hull has been speaking. 



Then about the striae going over hills and across valleys, one 

 gentleman who has addressed us said there is no movement in the 

 ice. I cannot help saying we are dealing with something which 

 has been so much investigated it is outside the region of con- 

 troversy. Professor Tyndall made a very careful series of ex- 

 aminations, and the exact rate of motion of a glacier has been 

 determined ; and not only has the rate been determined but the 

 reasons why ice moves have been pretty well worked out. 



Ice is one of those curious things which behaves in a curious way. 

 When water freezes it expands. Most other articles contract. 

 Water expands, and if you take out the ice at or about a freezing 

 temperature and crush it by hydraulic pressure you could crush it 

 into any shape. When the pressure is put on the ice yields ; it 

 becomes liquid; but it solidifies again immediately pressure is 

 taken off ; and, speaking from memory, I believe that Professor 

 Tyndall succeeded in squeezing ice into a lens, and other forms. 

 At the bases of heavy glaciers where you have ice hundreds of feet 

 thick in some places there would be enormous pressure at the 

 bottom. The ice at the bottom will be in contact with the earth, 

 and the upward convection of heat will tend rather to raise the 

 temperature of the floor of a glacier towards the bottom. The 

 pressure of the ice upon this will cause it to liquefy in the neighbour- 

 hood of the solid surfaces, and then solidify again immediately, so 

 that the glacier moves on. The ice at the bottom gets crushed by 

 the heavy pressure and the temperature at the bottom is at, or 

 near, the melting point because it comes in close contact with the 

 earth at the bottom. It has been proved, the ice where the 

 pressure is greatest, will melt underneath, slightly melt, and 

 solidify again immediately when it has got to a place where the 

 pressure is less. That helps to account for the flow of the glacial 

 ice. I do not know if that is the full explanation. There is 



