placed over the furnaces, and the steam was conducted along the paths of the houses in earthen pipes, and allowed at intervals to escape into the air of the house, and condense on the glass and plants. From this arrangement, which was expensive, no other advantages, as I have elsewhere stated', resulted (unless that the steam was more pure) than what are obtainable from pouring water on hot flues. Mr. Williams admits the steam to a vault, which is a very good method for supplying bottom heat; but a proper trial has not yet been made for heating the air of hothouses in the same manner employed at the cotton-mills and other manufactories in the neighbourhood of Glasgow. I have already mentioned the trials commenced at Kensington, and at the pineries of Mr. Andrews, by Mr. Fraser; and if he meets with that encouragement to which his knowledge of the subject, experience, and laudable desire of improvement seem eminently to entitle him, this elegant and healthful mode of supplying heat will soon become general not only in hothouses, but in all extensive concerns requiring an artificial temperature.

In respect to the objections to the use of steam in hothouses, I know of none that are not equally applicable to the introduction of steam in private houses or manufactories; and experience shows that these have been readily got over. The supposed trouble of nightly attendance in hothouses which Mr. Buchannau mentions, he also observes is rapidly giving way to improvements in the construction of the boilers and stoves. At Kensington no more attention is required in the nighttime than is requisite for a common furnace; and if one of Mr. Kewley's machines were adopted, there would only be the trouble of filling a large hopper with coals once in twenty-four hours, as Mr. K.'s apparatus would regulate the temperature of the house, and the boiler would regulate itself.

! Short Treatise on Hothouses.

• Mr. Buchannan in p. 293 observes, that "steam begins to come into use for heating hothouses," but does not refer to any examples. Since I began this part of these Remarks I have learned that Mr. Loddige, nurseryman at Hackney, is making arrangements to heat the whole of his extensive hothouses by steam.

I

Perhaps the difficulty of procuring and erecting the apparatus may deter some from adopting steam. But surely in Britain this must be an imaginary difficulty. In the most distant provinces it is only necessary to put Buchannan's work already mentioned into the hands of an experienced millwright, or to send him to examine some house or factory heated by steam. Near London every patriotic improver will of course employ Mr. Fraser, who has the greatest merit, and deserves every encouragement for having tried the scheme in the Royal Gardens at his own expense and risk.

I shall only add, as a general idea, that in large establishments where the mansion, the family stables, the farm, and the garden, are all at some distance from each other', it will be worth while to have separate apparatus for each of these departments. But in smaller mansions and in villas, where the whole are grouped together?, one boiler may serve the varied purposes of heating the hothouses, the mansion, and such appendages as baths, laundries, malt-kilns, cattlesteamers, poultry-houses, &c. It may also, if thought desirable, have arrangements which can be put in and out of work at pleasure, for ́impelling mill- and grind-stones, a thrashing-machine, turnip-cutters and washers, straw-cutters, a fire-engine in case of fire, and for effecting a variety of other purposes, one of which, very obviously useful, is that of forcing water to an elevated reservoir, so as to supply waterclosets, water-cocks, &c. in different parts of the house or hothouses, and jets-d'eau in the gardens. The principal apartments of the house and all the hothouses might be self-regulated by Mr. Kewley's machine; and for the general care of the engine, thrashing- and other machines, it will always be advisable to have a millwright3 on

'As at Woburn Abbey, Alnwick Castle, Harewood House, &c.

As at Garth House near Welch Pool, where an extensive range of hothouses (the only part of the design in which my plans were not followed) unite the mansion with the farm-yard and a range of circular stables, the latter perhaps the most elegant in England.

As most of the improvements in rural œconomy, and indeed in every branch of human art, depend much on the perfection and constant good order of machinery, I would suggest to country gentlemen the advantages to be derived from having a good millwright on their estates.

the spot with a labourer at his command. In this case a gasometer might advantageously be added, and the premises both internally and externally, as far as necessary for general use and occasional splendour, lighted with gas. The cost of a complete gasometer capable of supporting forty lights for four hours, and each light equal to ten candles of eight in the pound, is said to be 250 pounds'. Six pounds of coal produce light equal to one pound of tallow, and there remains the value of the coke. The cost of the steam apparatus depends much on the distance which the parts to be heated are from one another; but the additional comfort, and saving in the attendance and insurance, will generally far counterbalance the expense of the first

erection.

As it is not likely that steam will soon, if ever, become so general as to supersede in horticultural buildings the use of smoke flues, a few remarks are submitted on the improvements which have been recently attempted in the economy of fire heat in hothouses.

In order to obtain the greatest effects from a given quantity of fuel, Dr. Anderson in his patent hothouse (February 1801) proposes a large smoke chamber under or adjoining the house, so far not unlike the old Dutch practice already mentioned, but with the addition of an air chamber over or around it, and communicating by valves with the house. The plan is simple, and may occasionally be adopted with advantage. In various places attempts have been made to col

The nature of the employment of this superior class of mechanics leads them to think and judge accurately respecting mechanical operations in general;—there are few of the common machines of country carpenters and smiths that they will not improve on, and they are always ready to invent some expedient in a case of extremity. I consider myself fortunate in having at present a millwright, Mr. William Ward, as my foreman, very competent to heating by steam, lighting by gas, or to execute any improvement suggested in these Remarks.

'Clegg in Philosophical Journal, vol. xxiii. p. 86. Mr. Rucker's mansion near London, Mr. Lee's at Manchester, and Pitkellony House in Fifeshire, are heated by steam.. Mr. Lee's house, and Lord Gray's in Perthshire, are lighted by gas.

• At Abercairnie near Crief, Perthshire, in 1790; at Manchester about 1770.

lect part of the heat, which is otherwise lost or absorbed in the mass of brickwork containing the furnaces outside the house. The fuelchamber is surrounded by a vacuity, either communicating directly with the house a few feet from the furnace, or with an air flue or tube which conveys the heat thus collected, to the middle or opposite end of the house. Sometimes also heated air is generated by cast iron plates or tubes placed over or on each side the fire or furnace, on the same general principle recommended by Evelyn, Gouger2, and Chabannes; but as I have formerly observed, the warmth produced from very hot iron never being so wholesome as that produced from stone or earthen-ware, this variety merits adoption in but few cases. In general it may be observed, that the hot air introduced by air flues is so much deprived of its moisture when the fire is brisk, and so liable to vary in its temperature in the night-time, that it becomes unadvisable to use it exclusively as a mode of supplying heat; but in connexion with common smoke flues, the air flue conducted upon or around them, tends to equalize the heat given out to the house, which without this improvement is commonly much too great near the furnace. In foggy weather, and when the air is in a certain state in respect to exhalations and moisture, by opening the valves of the air flue, and admitting a stream of this exsiccated air, it may tend, Mr. Stuart3 observes, to prevent "damps and mildews." Wherever the introduction of heated air forms a material part of a plan, a hygrometer should be used to regulate the degree of moisture in the house; and care should be taken that the fuel chamber is in a state of perfect repair, otherwise smoke will sometimes find its way through crevices in the brick

At Archerfield in East Lothian, and various other houses near Edinburgh; and ingeniously varied at Mr. Henderson's nursery gardens at Brechin.

* See in his Méchanique du Feu, Paris 1713, a description of a chimney with the back, hearth, and jambs of hollow iron, to heat the air that is to enter the room;-also his plan of conducting the air so heated to different rooms, &c.

3

Specification of his Patent for heating and ventilating Hothouses and other Buildings,

March 1801.

work into the air chamber, where mingling with the heated air, it will be conveyed to the house, than which there is nothing more injurious to vegetation'.

With respect to improvements on smoke flues, none of importance have been recently made, that are not nearly coeval with their original introduction.

Mr. Stuart and the late Mr. Kyle observe, that the air ought to have free access to them on all sides, and that they ought to traverse the house lengthways as low and as near the front glass as possible. Mr. Stevenson3 has recommended flues of larger dimensions than usual in this country, but which have been long in use among the Dutch. Sir George Mackenzie recommends zig-zag or embrasure flues", which is in effect nearly the same with a plan I once tried of

By attempting to collect the heated air generated between the outer and inner furnace doors, in 1804 and -5, the description of furnace which I then adopted in the experimental house at Edinburgh before mentioned, became liable to this objection, whenever by change of wind or otherwise the fire did not draw well. As some plants were injured by the smoke and too great heat introduced in the night-time, a fine opportunity was thereby given to Mr. Nicol and others of the old school, with whom

"No crime so great as daring to excell,"

to decry indiscriminately in subsequent publications the whole system of heated air, double roofings, and other improvements, without displaying the slightest knowledge of the principles on which these improvements were proposed; but De mortuis nil, &c. Double roofings some of the Scotch horticulturists affect to treat with ridicule, and this with Professor Leslie in their capital, than whom no man has so ably shown in theory the immense advantages derivable from their use. See his Experiments on the concentric Cases, pages 373-8. By concentric hand glasses I have no doubt of being able to preserve a pine plant during winter in the open garden without the aid of artificial heat.

• Gardener to Baron Stuart at Moredun, whom Dr. Duncan mentions as an eminent promoter of gardening in Scotland, and who" used nearly fifty years ago to boast of producing every fruit in perfection but apples and pears." Mr. Kyle is author of a Treatise on Forcing Vines and Peaches, Edinburgh 1778, now very scarce,

3 Caledonian Hort. Trans. vol. i.

* See Fig. 6, PL. I. also the section of the Dutch serre chaude in Encyc. Méthod. plates to vol. d'Aratoire, &c.

Caledonian Hort. Trans. vol. ii.