walls, to exclude the frost from the blossom and the birds or flies from the ripe fruit, and also in the covering of flower-beds, hay-ricks, harvested corn, temporary structures for public assemblages, &c.

The length of these rolls at Syon is between 50 and 60 ft. but we have no doubt they might be made longer, since this depends on the diameter of the pole or rod (fig. 101. a), and the toughness of the timber employed, or its power to resist torsion. On one end of this rod and not on both, as is usual, a ratchet wheel (b) is fixed, with a plate against it (c) so as to form a pulley groove between (d), to which a cord is fastened, and about 3 in. further on the rod is fixed a third iron wheel, about 6 in. in diameter and half an inch thick (e). This last wheel runs in an iron groove (f), which extends along the end rafter or end wall of the roof to be covered. The canvass or netting being sewed together of a sufficient size to cover the roof, one side of it is nailed to a slip of wood placed against the back wall, that is, along the upper ends of the sashes; the other side is nailed to the rod (a). When the canvass is rolled up, it is held in its place under a coping (g) by a ratchet (h), and when it is to be let down, the cord (i) of the roll is loosened with one hand and the ratchet cord () pulled with the other, when the canvass unrolls with its own weight. The process of pulling it up again need not be described. The most valuable part of the plan is, that the roll of canvass, throughout its whole length, winds up and lets down without a single wrinkle, notwithstanding the pulleywheel is only on one end. This is owing to the weight of the rod, and its equal diameter throughout. By this plan a house 100 or 150 ft. long, might be covered with two rolls, the two pulleys working at the two ends; but if it were thought necessary, the two rods might be joined in the middle, and, by a little contrivance, the pulley and groove placed there, so as to work both of the rolls at once, from the inside of the house, from the back shed, or from the front. A more beautiful contrivance, for the purpose to which it is applied, we will venture to assert, is no where to be met with. It was constructed under Mr. Forrest's direction by Mr. Boughton, smith, Brentford End.

Such are the improvements that the Duke of Northumberland has made in his kitchen-garden at Syon; and it is important to remark that so promptly and judiciously were all the measures taken for their execution and so rapidly was that execution proceeded with, that in eight months after the work was commenced the whole was completed; the houses, borders, and walls were planted; the compartments cropped; the

walks finished; and every thing else connected with the kitchen-garden rendered as fit for the inspection and enjoyment of the family as if nothing had happened.

This magnificent range of forcing-houses may now, we think, be referred to as an additional evidence that metallic hot-houses are fit for every purpose of forcing; and we must take the liberty of saying what we have hinted at (p. 186.), that the public are greatly indebted to the Duke of Northumberland for having made this experiment, and that His Grace also has evinced a very superior degree of tact and discrimination, in adopting a description of structure, the superiority of which, though supported by the evidence of science and the opinion of some enlightened men, was yet opposed by a host of prejudices on the part of men both practical and scientific.

Though we inspected the different operations at Syon from time to time as they were going forward, yet we are, of course, indebted to Mr. Forrest for the dates and other facts which we have detailed. We should have a good deal to say of the merits of Mr. Forrest as the designer and successful and rapid executer of these works, were he not already sufficiently well known to the horticultural world. He has been engaged in works of this kind from his earliest years; and, from having received a better school-education than falls to the share of many gardeners, even those of Scotland, and been long accustomed to the management of numerous workmen, he has acquired those habits of arrangement and the division of labour, which are the only means of carrying on extensive and complicated works with that rapidity and successful result which have attended those at Syon. The great experience which Mr. Forrest has had in works of a similar kind under Mr. Macdonald, one of the very first gardeners in Scotland, at the Duke of Buccleugh's, at Dalkeith Park, and on his own account at the Hon. R. B. Stopford's, Barton Seagrove, Northamptonshire, and at the Earl of Grosvenor's, Eaton Hall, Cheshire, not to mention his botanical acquirements and his knowledge of the gardening of the metropolis while at work for several years in Kew Gardens, has not only given him habits of management, but cultivated his taste both in the art of designing kitchen-gardens and garden structures, and in laying out grounds; and the character of his mind has this particular excellence, that he embraces in his plans and arrangements every department of his art, and is not prejudiced in favour either of botanical culture, kitchen-gardening, forcing, or landscape-gardening. The Duke of Northumberland may certainly be considered fortunate in having employed such a gardener.

We must not omit to record the names of the manufacturers of these houses, Messrs. Richards and Jones, of Cheapside, Birmingham; they have evinced great ingenuity and practical skill in their construction, and will, we have no doubt, obtain the reward due to so much merit. We are inclined to think that some of the details of the rafters and sashes are improved on in the range now erecting for the Duke of Bedford at Woburn Abbey; but we shall wait till we see that range completed, and then, with His Grace the Duke of Bedford's permission, give an account of it similar to that now submitted. It is not to be considered surprising if improvements are introduced in a mode of construction comparatively new. The system of heating by hot water is undergoing astonishing improvements almost every day.

Those who know our preference for curvilinear iron hothouses will ask whether we should not have preferred the forcing-range at Syon constructed on that principle. Our decided answer is, that we should, on account of the lightness and elegance it imparts. We are not certain, however, that something would not have been lost in point of utility, at least for vineries and peach-houses, from the difficulty of constructing the roof so as to admit of the opening and shutting of the sloping part at pleasure, and of its removal altogether after the crop is gathered. If it can be proved that peaches and grapes may be grown and forced without the direct influence of the sun and the weather to the leaves and wood of the plants at any season of the year, then we decidedly prefer curvilinear houses for them; and as they are constructed without rafters, styles, rails, pulleys, cords, &c., they must, of course, come cheaper: but if the direct influence of the weather is essential, and we believe the majority of practical men think so, then we should prefer such houses as those erected at Syon and Woburn, heated by hot water according to the latest improvement by Mr. Weekes (see p. 544.), shaded during hot sunshine by a canvass blind in Mr. Forrest's manner, and covered during the nights of severe weather by garden shutters or straw mats in the manner of Mr. Shennan (Vol. III. p. 187.) and M. Lindegaard (Vol. IV. p. 414.).

When the magnificent range of botanical hot-houses now erecting at Syon are completed, we hope, with His Excellency the Duke of Northumberland's permission, to lay a similar account of it before our readers: at present that range is not permitted to be seen by the public.

REFERENCES to the Plan of the FORCING-HOUSES AT SYON. (fig. 102.) A, The general elevation; a b, the two peach-houses and three vineries; cd, the pineries and general forcing-houses; e, the gardener's rooms, and garden-library. BC, The general ground-plan.

1, 2, 3, Pine-pits, with iron and copper roofs, ends, and doors, the section of which may be seen at D. In this section will be observed the indication of the canvass blind described p. 510. On the back flue of these houses, cucumbers are grown in boxes all winter, trained on wires down the roof.

4, Peach-house, with table-trellis, the section of which may be seen at E. gg, rubble stratum; hh, air-shafts to rubble stratum; i, garden-walk.

5, Early vinery, the section of which may be seen at F. gg, rubble stratum; hh, air-shafts; and i, garden-walk, as before.

6, Medium vinery, the section of which may be seen at G. stratum, &c., as before.

gg, rubble 7, Early vinery; and 8, peach-house, with table-trellis; exactly the same as 4 and 5.. These five houses have the roofs, ends, and doors of iron and copper; all the trellises of iron, and also the cisterns and pathway. The roof trellis of the vineries is formed of wire in meshes, 24 in. by 8 in., the horizontal wires being 24 in. apart, and the sloping wires 8 in. The distance from the glass is 15 in. at the lower, and 16 in. at the upper part, of the slope.

9, 10, and 11, Pineries and general forcing-houses, the roof, ends, and doors of wood. Those structures having been newly erected on a different part of the premises, before Mr. Forrest came to Syon, it was judged best to retain them. Their section is shown at H.

13, Tan

12, 12, &c. The furnaces and stock-holes to all these houses. shed. 14, Mushroom-houses, with potting-benches in front. 15, Room for sashes. 16, Packing-room. 17, 17, Journeymen's bed-rooms, entered through the foreman's sitting-room. 18, Foreman's sitting and business room, with his bed-room and the garden-library over. 19, Room for shutters, sashes, mats, &c. 20, Room for flower-pots. 21, Potting-shed. 22, Room for keeping esculent bulbs and roots.

23, Tool-house.

24, Steam-boiler, a pipe from which leads the steam into every house, where it is delivered at pleasure, to fill the air with vapour, by the cocks k kk, &c. The advantage of having the steam-boiler heated by a fire which has no connection with the houses is, that steam can be applied in the summer season, when the fires are left off, without raising the temperature of the house. In the steam-boiler is a coil of pipe (p. 454.), connected at one end with the supply cistern, and at the other with the watering cisterns (17), by which, at pleasure, hot water is conducted into the early forcing-houses, for tempering the cold water for use, during the winter season. Ill, &c. Cast-iron cisterns, to each of which is a supply-pipe mm, &c., which is connected with a main pipe n communicating with the grand tank of rain-water o; and also a hot-water pipe from the steam-boiler, for tempering the water during the winter season.

PP, Gratings of the air-shafts in the front border, immediately within the edging of the walks.

9, The same gratings to the air-shafts which are placed within the house at the bottom of the back wall.

r, Open cast-iron work, serving instead of pavement for the footpath, the whole on one level. s, Stone pavement, also all on the same level. t, Doors into the back sheds for shifting, potting, &c., without taking the plants into the open air.

u, Main trunk of the steam-pipe, which serves incidentally to heat all the back sheds at pleasure. v, Box hedges, 2 ft. high, kept neatly clipped. w, Walk to pits. r, Walk to melon-ground. y, Level front walk. z, Main kitchen-garden walk, forming the approach to the forcing-range from the pleasure-ground. &, Pumps with troughs.