Smoke, a dense, elastic fume, which is exhaled from burning coals, wood, and other substances. Smoke being not only disagreeable to the senses, hut also frequently detrimental to health ; in genious men have contrived various means, by which the benefit of lire might be enjoyed, without the inconvenience resulting from such fumigation. - Having already stated some of these expedients, under the article Chimney (vol. i. pp. 517-18), we shall here add a few other methods, by way of supplement.

1. If the funnel be too short (which is necessarily the case in low buildings, as it would otherwise endanger the roof), it will be advisable to contract the opening of the chimney, so as to compel the incumbent air to pass through, or at least very near to the fire. Thus, the funnel will become warmed ; and the confined air, being rarefied by heat, will rise upwards, and maintain a proper draught at the orifice.

2. Another cause of chimnies smoking, arises from the injudicious position of a door. Hence, if the door and chimney happen to be on the same side of the room, and the former should open against the wall, the air will necessarily pass into the chimney, and expel the smoke into the room. This inconvenience will be felt particularly on shutting the door; the current being then considerably increased, to the great annoyance of those who may be near the fire. Such nuisance may be easily prevented, by placing a skreen from the wall round the lire-place, so as to intercept the air. A more simple method, however, is that of changing the hinges of the door, so that it may open the contrary way ; and thus occasion a current of air to circulate along the opposite wall.

Lastly, the chimnies of new Louses, for want of sufficient ventilation, frequently smoke to such a degree, as to render them almost uninhabitable. To remedy this unpleasant molestation, it has been proposed to draw down the upper sash of a window, for the space of an inch. As the frames, however, are generally fixed, especially in old houses, an expedient has been adopted, of cutting a circular hole in a pane of glass, and substituting a round plate of tin, suspended on an axis, and divided into vanes ; which, being severally bent in an oblique direction, are moved by the current of air 3 and the ventilator is forced round, in a manner similar to the sails of a windmill. This contrivance generally answers the end proposed ; but, as the continual noise is very troublesome, the following method has been preferably devised. It simply consists in taking out a pane of glass, and suspending it on hinges, so as to be opened and shut at pleasure; or, the pane may be set in a tin frame, and supported by two moveable joints on each side, serving the purpose of letting it down, or drawing up and shutting it, according to circumstances, having proper hinges at the lower part: thus, by opening such pane to a greater or less distance, the necessary supply of fresh air may be admitted, without exposing persons in the room, to the draught. - See also Fireplace.