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contrived to turn to the wind, commences one hundred yards from, and is conducted under ground to, the house; this supplies temperate air in winter and cool air in summer to all the different apartments, A tube on the roof, with a funnel contrived to turn with the wind, draws off or admits the escape of the wasted air from the different apartments. The same plan is used in the Derby Infirmary. In Mr. Strutt's house, the air on its introduction in the ground floor is heated by flues under the different floors of the first story. The whole ar rangement in regard to heating and ventilating, no less than as to the fitting up of the kitchen and offices, is unique, and is, or was in 1811, the most complete in England.

rooms.

The Marquis de Chabannes' principle of ventilation for private houses, and which he proposes to adopt also in hothouses, bears a near resemblance to Mr. Strutt's. He places a ventilator, which he calls an air pump, at the top of the house, to draw off by means of tubes communicating with the cielings of all the rooms in the house, the rarefied air; and at the bottom of the house he has a recipient or room, which in winter may be filled with hot air, and in summer with cold air, also communicating by tubes with the lower part of all the The tubes are of course furnished with valves, so that the temperature of each room may be regulated at pleasure. The air pump is kept in motion by wind, or by the smoke of the kitchen: chimney after the manner of a smoke jack. It is evident that, as the air pump draws off the air, its place must be supplied from the tubes communicating with the lower recipient, unless the windows or doors are open. This arrangement certainly admits of modification, so as both to serve for heating and ventilating hothouses; but the heat produced from hot water or steam being so greatly preferable to that produced directly from ignited fuel, and the action of the air pump, when there may be little or no wind or smoke, being rather doubtful, I am inclined to think a greater degree of perfection is to be expected from the mode proposed by Mr. Benford Deacon, with the improvements of which that mode is susceptible.

For warming and ventilating, Mr. Deacon' heats his air in boxes or chests of highly-glazed pottery tubes, or in boxes of tubes, or, double plates, or cellular masses of cast iron, immersed in a vessel of boiling water. To convey this air to the house, he employs a fan fixed in a semi-cylindrical machine, placed in the lower part of, or any where near, the house. With this machine he draws up the air of the atmosphere, forces it through the box of immersed tubes, where it receives the requisite degree of warmth or coolness, into a main communicating by tubes with the different rooms to be heated and ventilated. In ordinary cases, the fan-machine may be kept in motion by a jack or other similar engine; on a large scale, as for heating or cooling churches, &c. by manual labour. For cooling and ventilating, the air is drawn through a dry drain, or from a cool cellar, and the box of tubes is immersed in cold water, &c.

By distributing the conducting tubes under the floor, or even under the paths only, of a hothouse, and perforating them so as the heated air might rise as equally as possible, or by using tubes of canvass or woollen netting, and by leaving unputtied the interstices between the panes of glass; a very simple and, as it appears to me, a very perfect mode of heating and ventilation would be produced. It might of course be regulated at pleasure, and used either with or without the aid of smoke flues or steam tubes. In a large range, the boxes of tubes for heating the air might be immersed in steam, under or behind each house; and one fan, and one fire and boiler, erected in a centrical situation, might produce the whole effect. The arrangement would be such, that if by accident or want of fuel the fire got low, (though with a hopper furnace this could hardly happen,) then the motion of the fans depending on the force of the steam, the quantity of air driven through the box of tubes would be lessened in pro

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Specification of Patent 1812. These machines, which the inventor calls Eolians, are erected and answering the proposed ends at the Old Bailey, Albion Tavern, and Valpy's Printing-office. One will shortly be erected in a greenhouse at Streatham,

portion, so that there could be no clance of cold air being introduced through the fans continuing to operate when the water was cold or the steam off. I have no hesitation in risking an opinion, that withi the joint use of steam, this Æolian apparatus, and Mr. Kewley's regulator, a climate might be produced more perfect than any in nature, which would not only greatly improve the size and flavour of fruits, and the health and beauty of exotic plants, but might be of some importance in pneumatic medicine'.

But though the last plan merits adoption where perfection is aimed at, the present state of horticultural architecture, advanced as it is, will not in many cases permit of a system of ventilation so refined. The following plan, therefore, is submitted as adapted to general purposes; and which, excepting the introduction of glass tubes, differs little from the mode successfully practised by the Dutch, a nation tó whom we owe in a great degree our taste for, as well as knowledge in, culinary gardening.

Form a porch at each end of the house, a vault under it, or a shed behind it, of the same length as the glass, as in PL. V. Fig. 1. Let the back wall as in Fig. 3 have three tiers of windows or horizontal openings; the upper tier above the roof of the back shed, the lower tier on a level with the ground, and the middle tier under the upper angle of the back shed roof. These windows may be either boards arranged as Venetian blinds; or, glass windows hung with pulleys and weights; or large valves turning on pivots may serve instead of sashes. Form openings in the front wall of the hothouse and back wall of the shed, either glazed or boarded; and over all the outer openings stretch haircloth or wire gauze, to keep out winged insects, and to

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Dr. Adams, in the London Medical Journal about fifteen years ago, seems to have been the first who suggested the idea of constructing buildings of a graduated temperature for the benefit of persons of weak lungs. Subsequently Dr. Pearson and Dr. Buxton have attempted to carry the idea into practice in spacious apartments (Phil. Mag. 1813); and Dr. Kentish in 1813 proposed the establishment at Clifton of a sort of hothouse for invalids, to be called a Madeira House, which, however, has not yet been carried into effect.

soften or divide the air as it enters the house. This construction formed, I need not describe the modes of creating a current, either to interchange the air of the shed with that of the house; to allow the air of the house to escape by the upper windows, and to supply its place with that in the back sheds; or to form a general ventilation by the free admission of the open air.

But there are periods when it may become requisite to admit a small quantity of air in order to refresh the atmosphere of the house, when the upper tier of windows cannot be opened. This is to be effected by means of perpendicular glass tubes, or glazed grooves or recesses in the back wall, communicating at the bottom of the wall with a tube, which tube must be conducted across and touching the flue or steam pipe, so as to derive heat from it, and thence either outside the house or to the back shed, there terminating in a funnel mouth situated a foot or eighteen inches lower than where it crosses the flue. Such tubes may be formed of earthen ware. The perpendicular glazed groove should be continued from its junction with the other at the floor to the upper part of the back wall, and there terminate in a pane of tinned iron pierced with holes, or a piece of wire gauze; and in either case it may be covered with a valve. It is evident that the only time when such an arrangement will not pour down abundance of fresh air on that of the house will be when the valves are shut, when the sun does not shine, and when there is no heat in the flues; for the heat of the flue by rarefying the air in the earthen tube, and the rays of the sun by rarefying that in the glazed groove, will produce motion whenever the fires are lighted or the sun shines, according to the power of the existing causes. Distributive tin tubes might readily be conducted from these glazed grooves down the rafters, if thought requisite; and in houses glazed on all sides, where of course glazed grooves could not be used, tin tubes glazed on one side might be introduced (placing the glazed side next the sun) either among the plants on the stage or under the pendent trellis, or in various other situations, so as perfectly to effect the object in view. They might even be constructed outside the

house, where an outer curtain was used. The air introduced by these tubes would produce in the house an excess or overplus, which might either be let off by valves in the upper part of the back wall or roof, or left to escape by the crannies that necessarily exist in every house, and by the unglazed laps of the glass'.

Artificial regulation. Some attempts have been made with a view to this object; but, with the exception of Mr. Kewley's, they are so imperfect as not to require enumeration2.

The most beautiful and ingenious machine which has hitherto been proposed for the improvement of horticulture is the " Artificial gardener" invented by Mr. Kewley. The object of this machine is to regulate the temperature of every description of hothouse or frame, and is equally applicable to dwelling-houses for the same purpose. A thermometer is the first mover; it is placed within the atmosphere to be regulated, and the rest of the machinery fixed within or outside the house, and either near or at a convenient distance. The rising and falling of the thermometer operate on clock work; this last raises the plug of an elevated cistern, which communicating by a pipe with a cylinder and piston, raises the latter, and thus gives the power which it may easily be conceived is applicable to opening the sashes of the hothouse or hotbed, the valves or dampers of flues and steam tubes, &c. None of these machines have yet been erected in a hothouse near London; but Mr. Kewley tried one upwards of two years in his

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By forming such glazed grooves in the south elevations of dwelling-houses, and causing them to communicate either with the cielings of apartments to draw off wasted air, with cellars or dry drains to introduce fresh cool air, or with damp floors or partitions so as to prevent the dry rot, I venture to assert that a more powerful ventilation would be produced during sunshine than could be effected by any other means equally simple and economical, and so little liable to go out of repair.

• Mr. Barnstaple in 1790 adopted in the roof of a vinery, panes of glass suspended by an axle a little to one side of their centre. Repertory of Arts, vol. vii. Dr. Anderson in 1801 tied a flaccid bladder to valves for the same purpose. Patent Hothouse. Both answered the end, but in a very slight degree.

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