[Illustration: Fig. 3.--Diagram of bee cellar. Clearance 6-1/2 feet, ceiling 2-1/2 feet below ground level, packed with about 11 feet of sawdust.]
The ceiling of the cellar should be below ground level sufficiently to bring it below the level of frost. For the regions where bees should be wintered in cellars this usually will be at least 2-1/2 feet below the level of the ground (fig. 3). The ceiling should be 6-1/2 feet above the floor, just sufficiently high to permit a tall man to work with comfort. If the ceiling is higher it will result usually in too low a temperature at the floor. The ceiling then should be covered completely on top with some insulating material, such as sawdust, and if sawdust is used it should be piled on about 1-1/2 feet thick. Unless about this amount of protection is given on the ceiling it will be impossible to get the right cellar temperature during the coldest part of the winter. If the cellar is built in a sandy soil, it is possible to use the soil as a cover for the ceiling, in which event about 3 feet of soil should be placed over the inner roof of the cellar. The entire insulating material, of whatever kind used, should then be protected from rain and snow by having a roof over it. This roof should project at least 2 feet, preferably more, beyond the outside of the cellar wall, and provision should be made for currying off the water from the roof.
In case the beekeeper desires to build an apiary house over the bee, cellar, as is done frequently, he must provide a floor for this house at least at ground level, and he can not successfully use the ceiling of the cellar as the floor of the upper house. There is no objection to building a house above the cellar if adequate protection is given the cellar, but it must not be assumed that the house offers any material insulation to the cellar, for in most cases these houses are not heated in the winter. The relation of the house floor to the ceiling of the cellar is shown in figure 3.
Frequently the entrance is a weak spot in the insulation of the cellar, and it is useless to protect the roof and sides unless care is used in the building of the entrance. If the entrance is at the end or one side of the cellar, it will be necessary to build a sort of vestibule with double doors so that the heat of the cellar will not be lost rapidly. The heavier and thicker these doors, the better for the bees.