it is much more expensive than fig. 3, which, for practical purposes, is equally good, the only difference being the more finished and sprightly appearance of the former as compared with the latter.

ATMOSPHERIC HEAT OF VINERY.

At the present day there is no question that the best means for supplying this is hot water in pipes 4 inches in diameter. And let me here guard against the mistaken economy which is so often practised, of fixing too limited an extent of radiating surface to throw off a given amount of heat. This leads to the constant stirring of the fire to keep the water in the pipes as near the boiling-point as possible, entailing a far greater expenditure of fuel than if there were a third more pipe in the house. And it is well known to gardeners that a given heat from a moderately heated surface is more congenial to vegetation than the same heat derived from a more limited but highly heated surface. My own experience goes to prove that, in a vinery where grapes are expected to be ripe in March or April, there should not be less than one superficial foot of radiating surface for every 16 cubic feet of air the house contains. One foot in length of 4-inch pipe presents about one superficial foot of radiating surface. This would be something like four rows of pipe round front and ends of a vinery 13 feet high at back, 2 feet in front, and 13 feet in width, which are the dimensions of the early vineries at Dalkeith Palace, where a steaming-tray and ventilator, as shown in figs. 4 and 5, are also used. The tray is admirably adapted for supplying moisture to the atmosphere of the house, and is so far self-acting and regulating, that when the pipes are

at the greatest heat, and the house at the highest temperature, it gives off the greatest amount of moisture, and vice versa. The ventilator (fig. 5, page 11) is a plan I have devised and used during winter for letting a constant stream of air into the house, which, before it escapes

The water flows in the direction indicated by the arrow, ascending by the small pipe A into the tray, and by gravitation along the tray from B to C, descending again into main circulation by the other small pipe D.

amongst the foliage of the vines, must of necessity become as hot as the atmosphere of the house. To this mode of admitting a constant stream of air previously heated into our early vinery, I attribute to some extent the extraordinary fine flavour of early grapes we began to cut on the 1st of January 1862.

With regard to boilers, I think it unnecessary to say much; their name is legion, and many of them are good. My own observation has led me to prefer those that expose the greatest heat-absorbing surface, not under the fire, or by the side of it, but immediately over it, provided always that their construction is such that every portion of their heat-absorbing surface can be swept clear of soot and ashes daily; for if these are allowed to gather on the boiler, they will, as non-conductors of heat, destroy its heating power to the extent of the surface they

cover.

As a rule, it is much the safest plan to employ a respectable hot-water engineer to erect the heating apparatus, subject to specifications drawn by some one practically acquainted with the degree of temperature required, and the extent of pipe necessary to that end, the contractor to be bound to keep the whole in working order for one year after erection; and if at this date the boiler is sound, and the joints and valves all right, the inference is that they will continue so for many years.

The pipes should be painted a dull black colour, as being that most suitable for radiating heat.

The best stop-valves are those made by Messenger of Loughborough.

BOTTOM-HEAT.

Gardeners have for many years felt that it was exceedingly unnatural to place the branches of the vine in a high temperature, while the roots were in the cold soil of the border outside the house, and they have had recourse to various expedients to remedy this clearlyrecognised evil. Hot fermenting dung has been applied to the surface of the border, which did some good, more by its negative than its positive action, in so far as, if the heat from it did not penetrate the border to any depth, it at least, if applied in autumn, prevented the escape of the heat the border had derived from the sun during the summer. Wooden shutters, and in some instances glass, have been laid on the surface of the border to prevent the radiation of its natural heat. All these methods were well known to be very defective; and it is only of late years that the heating of vine-borders from beneath by means of hot-water pipes, as shown in fig. 1, has placed the temperature of the roots as com

pletely under the gardener's control as that of the branches has always been. Where the expense of stone pavement for covering the pipes is an objection to its use, the same end may be arrived at by first laying the pipes on pieces of half-inch round iron, resting on a smooth stone surface, at intervals of 9 feet apart. These bits of iron will act as rollers, and enable the pipes to expand and contract without the risk of "drawing" the joints. The pipes should then be covered with a small brick drain full of loopholes on each side, taking care that none of the covering bricks rest on the pipes. From these loopholes hot-air drains should be run right and left with dry bricks, or by using common drain-tiles, on the top of which 6 inches of brickbats should be laid, and then the turf, as already recommended. I find that the application of the bottom-heat for eight days raises the temperature of the border to 60°; and when this is indicated by the underground thermometer, the heat may be shut off, and will only have to be applied for a similar period when the vines are setting.

While the sixth edition of this work was being prepared for publication, a keen discussion, which originated in the columns of the Gardeners' Chronicle,' extended itself to the whole horticultural press, as to the advantages or disadvantages of artificially supplied bottomheat for vine-borders from hot-water pipes placed under the borders, either in chambers or amongst rubble. My own opinion, founded on experience, is, that the subject scarcely admits of discussion, so evident are its advantages if used with discretion, as every other appliance of the sort ought to be.

In the month of May 1868 I planted a cucumber-house with young vines, principally from eyes the same year.