452 0. D. von Engeln — Studies on Ice Structure. 



the ice will yield by flow without breaking. In this way the 

 ice can be permanently deformed. Moreover, once such flow 

 is initiated it continues for some time despite a progressive 

 diminution of pressure. This experiment was repeated a 

 number of times using cubes of ice ^-inch square. Thus on 

 January 16, 1912, air temperature 8°F., such a cube of pond 

 ice was inserted in the press and a pressure of 260 lbs. applied 

 in the direction of the principal axes. Nineteen hours later 

 the cube had flattened to one and one-half its original area 

 and pressure had fallen off to 230 lbs. In the cases of four 

 other similar cubes the pressures fell off to 223, 223, 230, 226 

 lbs., a strikingly narrow range. The cubes were reduced to one 

 half or one fourth their original thickness. Under the 

 petrographic microscope it was apparent that the original 

 crystal structure had been deformed, but the flattened ice was 

 apparently as strong (coherent) as the original pieces, although 

 the edges exhibited curved fractures parallel to the pressure 

 direction. Glacier ice flowed and flattened similarly but only 

 185 lbs. of pressure could be initially applied to £-inch cubes 

 of such ice and at the end of flattening the pressure was 

 about 159 lbs. As the air temperatures during these experi- 

 ments were 20°F. and lower, it would seem that the yield and 

 flow is not due to pressure melting and regelation unless this 

 be conceived of as occurring between the particles of the 

 crystal structure of the ice. 



Various kinds and forms of ice, also snow, were compressed 

 in metal cylinders to determine (a) whether any change in 

 crystalline structure could be brought about by pressure only, 

 and if so of what nature, and (b) whether actual continuous flow 

 of ice could be induced by pressure at temperatures sufficiently 

 low to render pressure melting and regelation inoperative. 

 Lead cylinders, open at both ends, were first used but these 

 yielded at pressures of 720 lbs. per square inch and the ice 

 within crushed as the cylinder sides bulged outward. In later 

 trials copper cylinders 4 inches in diameter, 12 inches high 

 with walls 1/16 inch thick were used. 



Into such a copper cylinder a rough-hewn plug of pond ice 

 was inserted with component crystals parallel to the length of 

 the cylinder, and water frozen in the space between the rough- 

 hewn core and the metal walls, making a solid ice filling. To 

 the ends of this cylinder a pressure of 500 lbs. per square inch 

 was applied, part of the load being borne by the metal edges of 

 the casing. The air temperature when the pressure was applied 

 was 17°F. and several hours later when the pressure was increased 

 to 720 lbs. per square inch it had fallen to 15°F. On the next 

 day at 9 A. M. the air temperature was 6°F. and no bulging of 

 the cylinder or falling off in pressure was apparent. Accord- 



