The best practical statement I have mot with about ventilation, say a writer in an English inagizino, was contained in the romarks of a mining engineer in Ponnsylvania: "Air is liko a rope ; you cnn pull it botter than you can push it ." All mechaniual appliances for pushing air into a room or a house aro disappointing. What we nood to do is to pull out the vitiatod air already in the room, the frosh supply will tako care of itself if moans for its admission are provided. It has boon usual to withdrnw the air througb oponings noar the ceiling - that is to curry off the warmer aud thercforo lighter portions, leaving tbo colder stratu at the bottom of the room, with thoir gradual accumulation of cooled carbonic acid undisturbed. A much bottor plan would be to draw this lower air out from a point near the floor, allowing the upper and warmer portions to desoend and take its place. An open lire, with a large chimney-throat, is the best ventilator for any room ; the one-half or two thirds of the heat carriod up the chimney is the price paid for immunity from disease ; and large though this soems, from its daily draft on the woodpile or the coal-bin, it is trifling whon ooinpared with doctor's bilis, and with the loss of strength and efficiency that invariably result from living in unventilated apartments.