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XXXIX. On the Modulus of Cohesion of Ice, and its bearing 

 on the Theory of Glacial Erosion of Lake-Basins. By R. 

 D. Oldham*. 



TAKING advantage of the late frost, I was able, through 

 the kindness of Mr. Hall, the manager of the Victoria 

 Lime and Cement Works, Rugby, to make a series of experi- 

 ments with a view to determining the modulus of the cohesion 

 of ice, so as to be able (reasoning from that) to determine 

 whether it would be possible for a glacier to scoop out a lake- 

 basin of any considerable size. 



Before describing the results of these experiments, it may be 

 well to mention the mode in which they were conducted. The 

 machine used was an ordinary cement-testing machine, which, 

 as used by me, was arranged as a simple lever of the second 

 order multiplying five times. From the nature of the machine, 

 it was impossible to arrange for a perfect counterpoise ; nor, 

 with the instruments at my disposal, could I make any accu- 

 rate determination of the initial pressure on the test; but I 

 was able to estimate it as not far from 20 lb., which I have in 

 each case added to the pressure indicated, in order to obtain 

 the full pressure on the test. The samples experimented on 

 were frozen in cubical moulds of 1J in. in the side, and were 

 for the most part perfectly clear and transparent, though just 

 in the centre they were sometimes more or less opaque. As, 

 however, this opaque portion was never more than J inch in 

 diameter, the error so introduced is insignificant ; and as the 

 specimens were exposed, in their frozen state, to temperatures 

 never rising above freezing-point for periods varying from 4 

 or 5 to over 24 hours, there could be no interstitial moisture 

 which would vitiate the results. 



A few words in description of the behaviour of these samples 

 of ice when subjected to increasing pressures may not be amiss. 

 As the pressure was applied, the ice did not seem to yield at 

 first ; but as soon as the pressure reached about 150 lb. on the 

 square inch, very evident signs of yielding showed themselves: 

 first a crack would form in one part of the cube, the sides of 

 which would slip over each other a little and then unite again; 

 the same process would be repeated elsewhere, and then again 

 somewhere else ; so that, by a continuous giving way and 

 reuniting, the ice would yield indefinitely to this pressure, 

 though it would not actually crush. It is the pressure at this 

 point which is noted in the Table below as the pressure at 

 commencement of yielding — not because I believe that no 



* Communicated by the Author. 



