ICE PHENOMENA. 419 



pands, and is forced perhaps six feet on to the shore, it is observed 

 that should the temperature again fall, this ice, which had previously 

 exceeded its limits does not recede to its former position, neither will 

 the main field separate over a few inches from the fractured portions 

 on the shore. On the contrary, should the temperature again sudden- 

 ly rise a still further advance of perhaps the same distance is made on 

 to the shore. 



This repeated expansion may occur many times during a winter, 

 and yet little evidence of any contraction will appear. I have knowTi 

 channels some six feet in width, opened for the purpose of isolating 

 the Rice Lake bridge, to be closed eight times within a month by the 

 expansion of the field ice. 



An extraordinary instance of ice piling was witnessed on our new 

 embankment. The ice shoved from both sides until the fractured pieces 

 met in the centre of the track. The embankment is twenty-six feet 

 in width at water level, and the rail is some six feet elevated ; as shewn 

 in the accompanying section. 



The next phenomenon of ice, and that which seemed the most per- 

 plexing and difficult to account for, is the fact of ice shoving from 

 different directions at different periods. In the first place it was 

 noticed that it rarely or never shoved or fractured towards the centre 

 of the lake ; but on the contrary, the ice on the shores of the lake 

 and of islands exhibited unmistakable signs of commotion. 



It is but reasonable to suppose that any solid, equally dense 

 throughout its dimensions, and susceptible of expansion, would, when 

 equally acted upon by the active agent or moving cause, expand from 

 its centre towards its circumference. We find such is the effect pro- 

 duced on any large field of ice of equal thickness and density, when 

 acted upon uniformly by either the mid-day sun or warm winds. It 

 is a fact, however, that it moves from other directions than from the 

 centre of the lake. Shoves are sometimes witnessed from the east and 

 sometimes from the west, to the north and to the south. 



