Page:Popular Science Monthly Volume 10.djvu/214

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neither, and if there is a fireplace it is generally closed up. Again, it is a mistake to suppose that foul air goes to the top of a room. Certainly the heated air goes to the top, but the chief impurity, the carbonic acid, falls to the bottom. There is nothing so efficacious in removing the lower strata of air as the ordinary open fireplace, especially if there is a fire burning. The usual defect in ventilation is the want of a proper inlet for the air. If the window be open, the cold air, being heavier, pours down into the room, causing draughts; if the door be open or ajar, the same thing occurs. The perfection of ventilation may be obtained in any room with a fireplace by simply providing proper inlets for the air, and nothing answers so well for the purpose as the upright tubes invented by Mr. Tobin. By this means the heavier external atmosphere ascends vertically through the tubes like the jet of a fountain, displacing the warmer and lighter atmosphere of the room, which finds its exit up the chimney. The tubes should communicate with the outer air on a level with the floor, and should be carried vertically upward in the room for about four or five feet. A constant supply of fresh air is thus insured without the slightest liability to draught, as the current goes directly upward until it strikes the ceiling. It is then diffused downward, mixed with the heated air of the ceiling. The same principle can be carried out in any room with a sash-window, by cutting out two or three holes an inch wide and three inches long in the wood-work of the upper sash where it joins the lower one. The columns of air ascend directly upward, just inside the window, and mix with the heated air in the upper part of the room. If this system were universally carried out, we should hear less of rheumatism and chills caught by sitting in draughts.

9. Persons should cultivate the faculty of detecting sewer-gas in houses. Typhoid fever is often caused by the escape of this gas into the house through defect of the traps and drains. However bad the drains may be outside of the house, there is little to fear, provided the gas can escape externally. The following two very simple precautions would naturally diminish the cases of typhoid fever: First, every main drain should have a ventilating-pipe carried from it, directly outside of the house, to the top of the highest chimney; secondly, the soil-pipe inside the house should be carried up through the roof, and be open at the top.—English Mechanic.



A CORRESPONDENT hands us the following anecdotes illustrative of the remarkable reasoning powers of dogs: The first case is one which occurred at a fashionable watering-place on the east coast of Ireland, some twenty years ago, and exhibits the remarkable sagacity displayed by a dog in carrying out the dictates