Cent.).

As it is evident that during the winter season the temperature of the air must frequently remain for days, and perhaps weeks, far below the freezing point of water, the fact that the water of the Lake does not congeal has been regarded as an anomalous phenomenon.

Some persons imagine that this may be due to the existence of subaqueous hot springs in the bed of the Lake--an opinion which may seem to be fortified by the fact that hot springs do occur at the northern extremity of the Lake.

But there is no evidence that the temperature of any considerable body of water in the Lake is sensibly increased by such springs.

Even in the immediate vicinity of the hot springs (which have in summer a maximum temperature of 55 deg.