Section III., 1915 [87] Trans. R.S.C. 



Crushing Strength of Ice. 

 By Professors H. T. Barnes, F. R.S.C, and H. M. Mackay. 



(Read May Meeting, 1915.) 



In a paper which one of the authors (H. T. B.) had the honour 

 to present before Section 3 of the Royal Society last year, the crushing 

 strength of ice was given as 363 lbs. per square inch. Efforts were 

 made to determine any difference in the crushing strength when the 

 pressure was applied both parallel and at right angles to the main 

 axis of the block. Comparatively small blocks were used in these 

 tests of approximately 6 inches, but no important difference could 

 be determined in the ultimate failure of the blocks, when yielding 

 in these two directions. 



It was stated that the blocks were heard to yield to the pressure 

 at approximately one-half the final crushing strength. 



In order to study the strength of larger ice blocks, one of the 

 authors (H.M.M.) placed the facilities of the McGill Testing Labor- 

 atory at our disposal. In this laboratory, a large Emery testing 

 machine gave us ample opportunity of testing blocks up to 14 inches 

 square. 



Through the kindness of Mr. M eld rum. President, and Mr. 

 Becket, General Manager of the City Ice Company, some great blocks 

 of clear St. Lawrence River ice were specially cut and supplied for the 

 tests. 



It was hoped to determine the effect of temperature on the strength 

 of the ice, and the blocks were placed in storage when the air temper- 

 ature was around — 20°F. ; but owing to the change in weather 

 conditions, which came shortly after, it was impossible to do any- 

 thing in that direction. It is hoped that further tests can be made 

 in this important matter, under more favourable circumstances. 



We think it worth while to record the results of our winter 

 tests, although we were able to examine only three of the large blocks, 



The details of these tests are given at the end of this paper. 



It will be seen that two of these blocks yielded at pressures much 

 under those of last year. This is probably due to faults in the blocks; 

 for it is exceedingly difficult to obtain such large blocks free from 

 them. The third block behaved much better, and ultimately burst 

 at 378 pounds, which is in very good agreement with the tests made 

 last year. 



