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bodied in an ice-house design to insure success are non-heat-conducling walls, the preventionof air penetrating the house from the sides and bottom, ample ventilation on top of the ice,good drainage at the bed, and proper appliances and arrangements for handling and stockingthe ice economically.
To make the walls as non-conductive of heat as possible and to prevent the passage ofair through them, an air-space, or a space filled with sawdust, shavings, ashes, or some non-heat-conducting material, is introduced in the walls. Layers of building-paper or tarred feltingare also employed. A combination of several of these methods is usually the rule. Wherean air-space is used provision must be made to keep the air pure by proper openingsaffording ventilation. Where the walls are filled in with sawdust or some similar material, it•is very essential to prevent moisture, as far as possible, from penetrating the filling material,not only on account of the damaging effect of the filling in that condition on the life of thewood in contact with it, but also owing to the fact that the presence of water increases theheat-conducting qualities of the filling material. Suitable holes under the eaves of the build-ing, connecting with the top of the spaces in the walls, should be introduced, so as to affordany moisture that may have penetrated the filling a chance to evaporate. A double roof is avery desirable construction, but, as a rule, the only protection against heat penetrating throughthe roof of the building consists of planking the roof rafters on top and bottom, creating anair space equal to the thickness of the rafters. The outside of the building should be paintedsome light color or whitewashed, as less heat of the sun will be thus absorbed. Doors andventilator openings should be located preferably on the north side of the building, whereverfeasible. Relative to the methods in use in American ice-houses for rendering the walls non-conductive of heat, it can be said, in a general way, that the width of the air-spaces or open-ings in the walls, to be filled with some insulating material, are too small to give the bestresults, and that, further, the insulation of the roof is usually very imperfect.
Good ventilation over the top of the ice is essential to prevent sweating of the ice. Itmust not, however, be created by a current of air, but simply be sufficient to keep the airsweet, as it is called in ice-house parlance, or, in other words, pure and dry. It is also advan-tageous to provide small board windows half-way down the sides, so that, when the level ofthe ice in the house gets below these windows, they can be opened during cold weather, or oncool nights, so as to purify the body of air at the lower level, the openings and ventilators inthe roof not affording, as a rule, sufficient ventilation when the ice is well drawn down. Thetop of the ice is kept from direct contact with the air by a layer of sawdust, salt hay, or simi-lar material. In the same way the sides of the ice pile are kept from direct contact with thewalls of the building.
Proper drainage of the bed on which the ice rests is very important, and it must be donein such a way as not to allow currents of warm air from the outside of the house to penetratethe bed and thus come in contact with the bottom of the ice, and also to prevent the coldair in the house from escaping through the drain, thereby allowing the warm air at the topof the house to descend nearer to the bed. This can be accomplished by a properly con-structed water seal in the drain-pipe or culvert, as shown in Figs. 157 and 158.
The floor in an ice-house should be higher than the surrounding ground, so as to keepsurface water out of the bed, and also to decrease the possibility of the warmth of the earth