A fire in an open fireplace is a good ventilator in a way. We may ventilate a room easily by raising the lower window sash, and by placing inside the frame a piece of wood 3-4 in. high, and 1 in. in thickness, and reaching from one side of the frame to the other. When the inside sash is brought down to rest on this piece of wood, it is thus raised 3-4 in. A current of fresh air moves inwards and upwards to the ceiling between the sashes, and if a piece of wood or glass, sloping upwards, be attached to the top of the lower sash, the current of air will be sent upwards to the ceiling, whence it will diffuse itself through the room. Draughts must be avoided; and it is wonderful how easily they may be prevented. Pettenkofer has shown that if air at ordinary temperatures does not move at a greater rapidity than 1½ ft. per second, its movement is not felt. What is needed, therefore, is some kind of screen that will not prevent the entrance of air, but that will break its force, divide its currents, and make it flow unfelt into the room. Perhaps the simplest plan of effecting this is the following: Open your window at the top to whatever degree is necessary to prevent closeness in the room, but if there is a draught open it wider still; place a little loosely-packed cotton-wool between the upper and lower sash, and in the open space above the upper sash place a strip of perforated zinc, with its lower edge turned upwards, so as to direct the draught towards the ceiling. If there is still too much draught, open it still wider, but fasten in front of the perforated zinc a screen of gauze containing loosely-packed cotton-wool. It is noteworthy that there must be a sufficient current to carry the air upwards along the slanting piece of zinc, and towards the ceiling, otherwise, as Corbett has pointed out, the cold air will trickle over the edge and cool the feet of the inmates of the room. In the hot months it is worth while to bear in mind the plan adopted by Martin in order to keep the rooms of the sick in a state of freshness. This consists in opening the windows wide, and then hanging wet cloths before them. The water, as it vaporises, absorbs the heat, and lowers the temperature of the apartment by several degrees, while the humidity which is diffused renders the heat much more supportable. By adopting this plan, the inmates find themselves, even in the height of summer, in a freshened atmosphere, analogous to that which prevails after a storm. This fact is well known to and utilised by the natives of India. Another plan is to close all windows facing the sun and cover them with blinds or curtains, to exclude the sun’s rays and the heated external air. Carpets may be replaced by matting, and the latter may be sprinkled with plain or perfumed water.