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This is a matter of no small importance yet how often do we see it treated, not only with indifference but upon the very worst principles possible to ensure its preservation ; not one ice house in fifty is constructed upon the correct principlesmdash;nof-one in the same number is managed correctly. When we consider that damp and heat are the two great agents of thawing, it should be our endeavor to counteract these by every means in our power. To effect this ventilation must be had resource to, and non-conducting materials employed in the erection. Of materials, we may observe that stone is of all others the worst timber and brick are the best. The usual practice ot sinking ice houses to a great depth under the surface is bad ; indeed, it has only one redeeming property, which is the convenience of filling from the top. Its advantages are, the difficulty ot admitting sufficient ventilation to correct the dampness, which, build them as we may, is sure to exist in underground houses, the conduction of heat from the surrounding soil, and the difficulty of effecting sufficient drainage; these very far overbalance the advantages thus offered. Why are the majority of ice houses and most cellars during winter so much warmer than the surrounding atmosphere? Is it not irom the heat conducted through their walls from the surrounding soil? Earth is a much better conductor of heat than air, or, in other words, it communicates its heat to other bodistf coming in contact with it much quicker than that element. Hence the necessity of placing be- tween the earth and the ice some slower conductor of heat, and the slowest conductors we have applicable to the case are timber.charcoal or air ; both also resist damp, while stone does not, and, besides, it is a rapid conductor of heat. Water is also a rapid conductor of heat, and instances have been known, where rain water has percolated the roof oi an ice house, that the temperature has been raised to sixty degrees. Hence the necessity of keeping such houses perfectly dry, not only at the top but also throughout, by efficient drainage of the melted ice, and by ventilation to correct the dampness in the atmosphere and walls. Indeed, the walls of an ice house, to be in proper condition, should be as dry as those of a dwelling. The cheapest and best way of constructing an ice house is to make its walls double with a space between them, which should be filled with that excellent non-conductor, " charcoal dust." Where timber is cheapest the house should be boarded inside and out, with the charcoal dust between the walls; where bricks are cheapest they should be used. Stone may be safely used with such a good non-conductor between a double wall. Dry saw-dust is also a good non-conductor, and it can easily be obtained everywhere in our country, but it should not be used unless it is perfectly dry.
