Heat distributing tanks for retarding surface freezing

A fountain for providing stock access to water under water freezing conditions, comprising:

• a tank having dimensions of approximately one foot in diameter and one foot in length, and of heat conducting material for placement in the water,
• means carried by said tank for ballasting said tank with an end of said tank adjacent the surface of the water,
• a volatile fluid within said tank in a quantity of about one tenth of the volume of said tank,
• said volatile fluid having boiling and critical temperatures below the freezing temperature of the water,
• whereby said volatile fluid is vaporized by the heat of the warmer water adjacent the tank away from the surface and is condensed by giving up its heat to the cooler water adjacent the tank adjacent the surface to retard its freezing,
• thermal insulating collar means surrounding said tank, said collar means being of length less than the length of said tank, and of diameter larger than said tank to enable said tank to freely float therewithin, to contain the heat given up by the condensing volatile fluid to within said collar, and,
• means for ballasting said collar means to float with a portion thereof above the surface of the water, whereby the tank can be displaced by the stock for access to the water within said collar.