The annexed engravings are views of improvements in warming and ventilating buildings, taken from Newtons Repertory of Arts Inventions, London. It is a sabiect which is frequently urged upon our notice by correspondents, and we endeavor to embrace every opportunity to present something that may be of general interest. Figure 1 is a front view of an open fireplace with the arrangements for ventilating. Figure S is a vertical section thereof. Figure; 3 is a vertical section of a plan of carrying out the improved mode of ventilation, and figure 4 is a view of the system applied to a chimney in a dwelling where a stove is used. In figures 1 and 2 the fire-place consists of a box made ot sheet-iron, lined with firebrick ; the lower end of the fire-brick is in clined outwards for the purpose of reducing the capacity of the fire-place without diminishing the radiating surface. The grate is placed in the usual recess under the chimney the lower end of which is closed—as in figure 2—leaving only an opening for the metal flue, /, of the fire-box. The space, E, round the grate, is cloeed in front by a plate, so as to form a close chamber into which air may be admitted from the lower part of the room, at the openings, ? ?, figure 1, such openings being lurnished with slide valves, to be opened and closed at pleasure. From the upper part of the space, E, there rises a pipe, F, the upper end of which communicates with the upper part of the room near the ceiling, as shown in figures land 2. It will therefore be understood that cold air may be admitted; to the space, E, through the holes or openings at B, and after being warmed in the space, E, it will pass up the pipe, F, into the room. A continuous current is thereby produced, so that the air admitted to the space, E, is not burned, but merely warmed before it issues into the room. If by this arrangement the atmosphere of the room is rendered too warm, it will only be necessary to close the openings, ? B, by means of the slides, and then there will be no current of air through the pipe, F. The same arrangement may also be employed for ventilating the room, for which purpose it will only be necessary to cause the vitiated air in the upper part of the room to pass do wn the pipe, F, into the space, E, whe. it will be conducted into the chimney by the short pipe, G. This pipe has its mouth bent to keep the soot from falling into it; but a better plan is to have it straight with ? cap over it. This short pipe is furnished with a throttle-valve, A, which is worked by a button, t, and when the room requires ventilation, it will only be necessary to open the valve, A, and close the valves, ? ? ; the heated air of the room will then pass down pipe, F, into the case, E, which is filled with hot air, and the vitiated air lrom the room will then pass up the chimney through the pipe, G. When the room requires warming, the throttle valve, A, must be closed and the slide valves, ? ?, opened when the cold air will be warmed by contact with the heated sides of the case, E, and it will then ascend by the pipe into the room. In figure 3 the lower aperture of the chimney is not closed as in figures 1 and 2, and the construction ot the fire-place is such that it may be applied to any chimney without the necessity of closing the bottom part. In figure 3 the fire-place is enclosed in an outer casing so as to form a space, E, between the outer and inner casings, into which space air is admitted either at the bottom or from the upper part of a room. The tube, F, which conducts the vitiated air from the room terminates at the bottom in this chamber.— When it is required to warm the air of the room by passing a portion of it through the space, E, air is admitted through a branch side pipe into said space. The branch pipe which admits the air into, E, below, has a valve in it to regulate the quantity of air to be admitted, and to open and close the communication. The room can be ventilated by closing the valve which admits the cold air below by the pipe into chamber, E, at the back of the fire, when the hot air from the upper part of the room, will pass down pipe, F, go into chamber, E, and pass away by an opening at the back up into the chimney.— This mode of heating and ventilating rooms is upon the syphon principle; one which is old and well known, but which may, as shown, be applied in many ways. In figure 4 the stove, S, is of any of the known forms—it looks much better in its plain unpretending style than the florid ornamental stoves in common use. The pipe is inserted in the chimney which is closed at the bottom to exclude any air except that which passes through the stove. The syphon pipe is shown at F. It is furnished with a Vatve, A, and buttan, i, for opening or closing communication with the room. The heat of the chimney is sufficient to rarefy the air in pipe, F, and thereby cause a draught from the room, which will by this means be ventilated. The stove is a close one the door opens in front of the circular grate, and it is made of wire gauze which acts as a blower.— The ventilation is shown as applied to the stove ; the heating of the air by the grate plan being accomplished by the stove itself, which is placed in the room, and which, on this account, as is well known, heats a room with far less coal than a grate in the chimney. The fire-place with a grate, however, is the most cheerful plan, and is the one in general use in this city in sitting rooms, parlors, &c. The greatest part of the heat generated in a grate goes up the chimney, and is lost so far as any benefit is derived from it by persons in the room. Dr. Arnot, by exposing ice in a chimney made the discovery, that more of it was melted in a given time there than in the room ; this led him to invent the stove which still bears his name. Great attention should be paid to the best methods ot economizing fuel, and proper ventilation. We have often directed attention to these questions by illustrating Ruttans system, and in the notice which we presented two years ago, of Dr. Griscoms work on the subject. We have only to add at present that if all stove doors were made to open in front of the grate, and had a slit in the lower part to admit air by a wire gauze screen under the grate to supply the oxygen requisite forcombustion,a greatim-provement would be effected. The coals could be fed in at the top, and the door used only for cleaning out the contents of the stove with a shovel. The door should be small and made with ribs lastened to it inside. The common ash pan cannot be dispensed with. A proposition has been brought before Congress to purchase 100 fire annihilators for the use of the navy. The price will amount to $2,500 for the large size. Beet root sugar is now made successfully in Ireland.