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portion, so that there could be no cliance 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 pueumatic 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 pernit 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 to 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

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. Dis, tributive 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

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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 enumeration?.

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 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

power which

' 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 cel. lars 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.

own garden in the Isle of Man, and has one in constant use for

regillating the temperature of his apartments at his present residence'. This machine has been shown to Sir Joseph Banks, who thinks it will answer the purposed end; and I need not inform my reader of the value of the opinion of one so eminently qualified to judge, and whose extensive observation and experience have enabled him to

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of new inventions with such certainty that, as Sir Humphry Davy has remarked, it

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be considered in him a sort of intuitive faculty?.

The importance of tradesman-like workmanship, or sufficient EXECUTION, has been already noticed. The remarks to be submitted on this subject relate chiefly to those variations of construction which I purpose introducing in hothouses. In the

masonry of hothouses particular attention should be paid to the foundations. A very common cause of decay is rents and settlements in the front wall, which of course receives the greater weight and thrust of the roof. The foundations of these walls ought to be deeper than usual, because the ground is liable in the course of cultivation to be stirred two or three feet deep; and the wall does not

generally rest on its whole base, but on piers at certain distances, in order to admit the spreading of the roots, &c. Where rafters or uprights are used, I should recommend a pier under each, fourteen inches square under ground, and above ground of smaller dimensions, according to the weight to be supported. Instead of an arch from pier to pier, it will, in all cases where air is to be admitted by openings in the front wall, be preferable to employ stone imposts, and also to have that part of the pier which is above ground of one stone nine or twelve inches square, according to circumstances: see Pl. X. Figs. 1 and 2. The object of this arrangement is to increase the pasturage of the

No. 7, Providence Buildings, New Kent Road. As soon as the machines are ready for sale, one will be erected here for the inspection of my friends.

• In a Lecture at the Royal Institution, speaking of the tannin found in terra Japonica.

roots at a, a, and the opening for admitting air at b, b, Fig. 1 ; and by having the stones properly rabbeted, to render wooden frames for the shutters of these openings, or wall plates for the rafters or astragals to rest on, unnecessary. The exact form of the upper surface of the wall plate must depend on the sort of rafter or astragal to be fixed on it. In general it should be such as will deliver outwards into a light gutter suspended from the stone, all the water of condensation which may run down the rafters or astragals.

In regard to the sort of stone to be used, each district has its local facilities for that material; but where there is not a good stone near the spot, and water carriage is not far distant, I should recommend a stone which in point of durability and strength surpasses the Portland; and differs from it chiefly in having more sand in its composition, and being of a yellowish colour. This stone is to be had in great abundance from Colallo in Fifeshire, and may be worked there to any form, and laid down in London so as to come considerably cheaper than Portland stone'.

The doors and openings for ventilation in the other walls should also have their sills, cheeks and lintels, of stone, properly rabbeted, so as there may be no wood-work required but for the shutters or doors.

Where pavement is used, I should recommend, as preferable to any pavement I have seen, the Arbroath flag-stone. It may be had in very large masses, which is a great advantage; and is so little absorbent of moisture, that even when laid on damp ground it always appears dry and comfortable.

The wood-work of hothouses such as I recommend, where improve

· It has been extensively used in the Penitentiary at Millbank, and various other places; and specimens may be seen at Mr. Stoddart's, Strand. The present proprietor of this invaluable quarry, Mr. F. Braidwood of Edinburgh, has not yet been able to make it sufficiently known; in doing which he of course experiences great opposition from the proprietors and advocates of Portland stone. Excellent specimens of this stone, and also of the Arbroath pavement, may be seen in the greenhouse erected here (Bayswater) already referred to.

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