88 DR. ROBERT BELL 
Frazix (ANCHOR) IcE.—This species of ice is familiar to almost every one in Canada. 
It forms, as a spongy mass, in cold weather, on the stones in the bottoms of open rapids, 
in brooks and rivers, and sometimes under the open water, which is often found at the 
outlets of lakes. In clear weather, it gathers abundantly around the boulders, and when 
these rest on other stones or have only a narrow base of support, they are sometimes 
buoyed up by their icy envelope and floated or rolled away by the force of the current. 
Boulders of considerable weight have sometimes been known to be lifted by this means. 
When the weather becomes milder, or the sky overcast, the frazil rises to the surface 
or floats off like a mixture of snow and water. Although the water may remain open 
beneath bridges or over-hanging rocks and large fir trees, frazil is not observed to form im 
such situations. The cause of the formation of frazil had never been satisfactorily 
accounted for, so far as the writer is aware, until Dr. Sterry Hunt mentioned to him that 
he regarded it as due to terrestrial radiation and to be analogous to the formation of hoar- 
frost on the surface of the ground in clear weather. As long as rapid radiation is going 
on, the surface of the submerged stones will have a sufficiently low temperature to retain 
the ice. The chilly water supplies abundant material. In rapids, the surging and 
churning motion would carry down the coldest water from the surface, probably charged 
with multitudes of fine ice-crystals, and throw it against the stones in the bottom, thus 
aiding the process. If this view of its formation be correct, the loosening of the frazil in 
mild or overcast weather would follow as a consequence—as well as the fact that, so far 
as we are aware, frazil does not form under obstructions to radiation such as those which 
have been referred to. 
At rapids in small rivers, where the bed of the stream is filled with boulders, the 
writer has frequently found a narrow and straight channel, sufficient to contain the 
whole stream at low water, excavated among them by the removal of the boulders. The 
latter are piled on either side, especially towards the lower end of the current, and they 
have evidently been buoyed up and rolled out of the bottom of the rapid. Judging from 
their various stages of weathering, and from the different quantities of moss and lichens 
growing upon them, these boulders have evidently been deposited along either side of the 
channel in many different years, showing that the process of excavation has been a gradual 
one. Some of them look as if they had been newly cast out of the bed of the stream. 
The phenomena, just described, are particularly observable in the numerous small rivers 
north of Lakes Huron and Superior and are probably due to the action of frazil. 
Lona OPEN FissuREs.—These, as occurring in the ice of our rivers and lakes, are 
familiar to all who have had occasion to drive much on our winter roads. These singular 
rents sometimes extend for miles, almost in straight lines. They usually make their 
appearance in the early part of winter, and their original formation is said to be accom- 
panied by aloud report. Once established, they remain open all winter, or are covered 
with only a thin film of ice, and their width generally increases, until the greatest cold 
is past. They are often a source of trouble to lumbermen and other travellers on the 
ice, since wooden bridges require to be thrown across them where they intersect the 
winter roads, their width being often from five to ten feet. Their formation has been 
ascribed to sudden changes in the temperature of the air. If this view were correct, we 
should expéct these cracks to open or close with every subsequent rise or fall in the 
