334) Dr. LeConte on a remarkable Exudation of Ice 



phaenomenon, under proper circumstances. Jt is seldom, if 

 ever, observed in rich, mellow, alluvial soils, abounding in 

 vegetable matter. 



3. The general appearance of the phaenomenon is that of 

 a vast number of filaments of ice, forming in their aggregation 

 fibrous columns resembling bundles of spun glass, emanating 

 at right angles to the surface, as if protruded in a semi-'fluid 

 state from an infinitude of capillary tubes in the ground. The 

 structure of the columns is distinctly fibrous, presenting a fine 

 silky, wavy, silvery surface, analogous to that of the fibrous 

 variety of gypsum. They exhibit various degrees of dia- 

 phaneity, apparently depending on the purity of the water as 

 well as on the state of aggregation of the icy filaments; being 

 in some situations almost perfectly transparent, and in others 

 scarcely semi-pellucid. Sometimes the fibres composing the 

 columns are readily separable; at other times they are, as it 

 were, fused together. When examined by transmitted light, 

 transverse strice are observed to cross the filaments at intervals 

 varying from y\jth to Jjjth of an inch. A thin stratum or 

 crust of loose frozen earth is frequently detached and elevated 

 on the summits of the columns, often forming a continuous 

 roof-like covering to the soil beneath, extending over many 

 square yards ; at other times appearing in separate and iso- 

 lated flat caps of variable size. The columns are not always 

 uniformly distributed over the surface of the ground, but fre- 

 quently exhibit considerable intervals of unfrozen soil between 

 them. When the exudation takes place around the margins 

 of a circumscribed depression containing water, like that left 

 by the foot of a horse, it appears to draw up the water from 

 the cavity, leaving an interior grotto lined with fantastic 

 groups of icicles. The icy columns vary in length from one 

 to thr€e, four, or even five inches, according to the favour- 

 ableness of the situation and the intensity of the cold. They 

 vary in size from mere threads to prismatic bundles of one- 

 fourth of an inch in diameter. When very long they fre- 

 quently fall over by their gravity, presenting a beautiful ap- 

 pearance when viewed in masses. The effect produced by 

 walking over a surface on which the phaenomenon is well- 

 developed is very striking. The superior crust of frozen earth 

 and its supporting icy columns give way under the foot, which 

 thereby sinks several inches below the apparent surface at 

 every step. When the phaenomenon occurs along the preci- 

 pitous sides of the ravines and road-side cuts, the earth which 

 has been elevated falls down to the bottom of the inclined 

 plane as soon as the sun takes effect, leaving a fresh surface 

 of soil exposed to the action of the next frost; and as this ex- 



