Sir William Edward Rous Boughton has erected a house or pit at Downton Hall, similar to that of Mr. Knight, but rather wider.[2] Pines are grown in it on Mr. Knight’s plan, but the plants were not in a thriving state in November last. Charles Holford, Esq. of Hampstead, is also a disciple of Mr. Knight as to the culture of this fruit, but he has not yet been very successful. [2] The roofs, both of this house and that of Mr. Knight, were furnished by Messrs. W. & D. Bailey, of Holborn, London. SECT. II. _Of other Improvements in the Culture of the Pine Apple, by different persons._ We shall first notice the improvements which respect bottom-heat, and begin with noticing an attempt made by Mr. Thomas Jenkins, of the Portman Nursery, London, to warm both the pots in which the plants are grown, and the air of the house, by the heat generated by fermenting stable-dung placed in a vault beneath. It is only within the last three years that Mr. Jenkins has begun to grow the Pine Apple to any extent; he brings forward the plants in hot-beds and deep frames, inclosing beds of tan, and heated by linings of dung. As an economical part of the construction, we may mention that he substitutes wattled hurdles for the lower part of the frame, in contact with the tan, by which means a saving in the first cost is effected, and the heat of the dung penetrates much more readily to the tan. [Illustration: 21] Most of the plants are fruited in these pits, but some are fruited in a house, (_fig. 21._) which “though furnished with flues, yet these have been very little used. The heat imparted to the plants is produced by the fermentation of stable-dung in a pit below the plants, the top of which is covered by tiles supported by iron rafters, with the joints closely cemented, to prevent the passage of steam into the house. The pots are neither bedded in tan, nor in mould, but stand on the tiles, and the interstices between them warm the air of the house.” [Illustration: 22] The dung is managed as in West’s pit (_fig. 22._), but with the addition of being watered after it is thrown in, which is found to promote fermentation, and the intensity of the heat. One of the earliest instances of steam being used as a bottom-heat with which we are acquainted, was that by Mr. Butler, gardener to the Earl of Derby, at Knowlesly, near Liverpool, in or about 1792. It had been used twenty years before, but chiefly for other purposes. Speechly, in 1796, knew only two instances in which steam was applied as bottom-heat; and, with M’Phail, does not think it will finally answer as a substitute for tan. Instances in which it is adopted, are now much more numerous; but time sufficient has not elapsed, and the opinions of gardeners are yet too unsettled on its merits to enable us to recommend it for adoption in general practice. For heating the atmosphere of hot-houses, there seems little (or at least much less) doubt of its being preferable to fire-heat.