158 Messrs. R. M. Deeley and P. H. Parr on 



b, and the glass rod was found to have embedded itself in the 

 ice ; most of the water produced by the pressure beneath the 

 glass had found its way to the upper side and the pressure 

 being relieved it had frozen there. Before putting the glass 

 bar in position a groove was melted along the top of the ice 

 bar and in this groove the glass bar was placed. 



Tarr and Rich found that when the temperature was a few 

 degrees below the freezing-point the rate of cutting was very 

 slow, and when the pressure was also small the rate of cutting 

 became almost unmeasurable. It is, therefore, very important 

 that the experiments should be made at or very slightly above 

 the melting-point. In the experiments, the results of which 

 we give, the atmospheric temperature was about 15° C. and 

 no freezing mixture was used. 



Taking the case of the Hintereis Glacier we have, at 

 Bliimcke and Hess's section V., estimated the slip to be 



