In the polar regions (we quote from Dr Child) snow supplies the ever-ready material out of which the Esquimaux construct their houses, and hardy explorers extemporise the huts in which they find shelter when absent from their ships on distant expeditions. Nor are the ships themselves considered "snug winter quarters" until their sides have been banked up in walls of snow, and the roof raised over the deck has been thickly covered with it. Snow huts are warmer than might have been expected. If built upon ice over the sea, their temperature is sensibly influenced by the heat of the unfrozen water below, which is said seldom to fall much under 40º F. in any part of the ocean. Even where the external temperature has sunk to 20º or 30º below zero, sufficient warmth is produced in a snow hut by the huddling together of three or four persons within it. When Dr Elisha Kane, the American explorer, passed a cold arctic winter's night in a hut beyond Smith's Sound, the temperature produced by its complement of lodgers, and two or three oil lamps, reached 90º F.; so that he was compelled by the heat to follow the example of the rest of the party, and partially to divest himself of his clothing. Yet in lat. 79º N., Dr Kane marked a temperature of 75º below zero in the month of February. No fluid could resist it. Even chloric ether became solid, and the air was pungent and acrid in respiration. RED SNOW. As if it had been ordained that there should be nothing absolute in nature, snow itself, the very type of whiteness, sometimes exhibits the most curious colouring. Who, for instance, has not heard tell of _red snow_? Its existence was even known to Pliny, the great Roman naturalist, and he attributed it to a dust with which the snow became covered after it had lain several days on the ground. "Snow itself," he says[13] "reddens with old age" (_Ipsa nix vetustate rubescit_).