378 NON-CRYSTALLINE ICE COLUMNS—MACGREGOR, 
been explained. Attention was drawn to the occurrence of ice in 
erystalline columns rising from the soil and bearing pebbles and 
earth on their summits, by Sir David Brewster,* but the columns 
referred to above, were distinctly non-crystalline. In the earlier 
volumes of Nature (vols. XXI, XXII, XXV, &c.,) there is a long 
series of communications describing and discussing peculiar forms 
of ice, but for the most part they refer to the familiar occurrence 
of ice in the form of filaments springing from rotten wood or 
from a porous, clayey soil. The only description of the mode of 
ice formation referred to above, which I have been able to find is 
by J. D. Paul.+ He describes ice as occurring in bundles of little 
rods rising from the frozen soil and carrying dirt and pebbles on 
their summits. He also mentions their being curved, but does 
not refer to any uniformity in the direction of their curvature. 
Nor does he give any explanation of the phenomena which he 
observed. 
I have frequently observed this mode of ice formation in Nova 
Scotia, and in most respects the present case is similar to others 
which have come under my notice. But my attention was never 
before directed to the fact of the upward curvature of the little 
columns. And it is this observation, together with the simplicity 
of the conditions under which, in this case, the little columns 
were produced, which have led me to bring the matter before the 
Institute. 
A short time before the date of the occurrence referred to, the 
ground in front of the College building, which had become quite 
hard through the trampling of many feet, was covered with a 
thin coating of loose pebbly soil for the purpose of making it 
more level. This layer of soil had not been rolled, and had been 
but slightly walked over, when several days of heavy rain 
ensued. As the hard soil underneath prevented the escape of 
the rain, the loose soil must thus have become quite saturated 
with water. Then came one of our sudden changes of temper- 
ature. The wind whirled round from the south to the north- 
west, and the temperature fell from many degrees above, to sev- 
* Edinburgh Journal of Science, N. 1X., p. 122, and Poggendorfi’s Annalen, Bd. VII., p. 509, 
t+ Nature, Vol. XXXI, p. 264. 
