bottom heat, is preferable to the use of fermenting materials; because the results in each case, are more perfectly under controul. Whilst on this part of the subject, I may be allowed to mention an error which is somewhat prevalent: We frequently hear of the humid nature of the heat given off by hot water pipes, in comparison with that derived from such appliances, as a flue; it is not unfrequently asserted, that the heat thus derived is so moist, so genial, so peculiarly adapted to plants: there can be no doubt but that the heat thus obtained is infinitely preferable to that obtained through the medium of flues, generally speaking; but its superiority consists rather in its purity, its freeness from noxious gasses, than in its possessing a greater degree of moisture. Heat—that is—caloric, is the same, whatever may be the medium by which it may be conducted; and in the case of hot water pipes, they give off that which has been conducted to them by the water, directly from the fire, the water acting as a mere conductor; it is difficult to conceive any thing more thoroughly devoid of moisture than the heat thus communicated: let any one who doubts this, place a damp cloth on a series of hot water pipes when in action, and the result will soon work conviction. With these general remarks, I will proceed to describe the kind of structure which I regard as being peculiarly adapted to the growth of Cucumbers; and notice some of the conditions which it is necessary to keep in view: the engraving on the next page, represents such a structure.

The aspect of the Cucumber house, should be nearly S.S.E; or in other words—it should be so regulated between the points south and east, that whilst the rays of the sun will be admitted as fully and as early as possible in the morning, there may be no obstruction offered to their more powerful action as that body approaches the meridian. In the growth of all tender plants, light and sun heat are required during the winter months as well as in summer, and there can be no greater error as regards the erection of structures devoted to such purposes, than to provide for their admitting the direct rays of the sun in the earlier part of the day, at the expense of refracting and thereby weakening, to a greater degree than is really unavoidable, the power of the noon-tide rays of that invigorating and life-sustaining agent: during the summer months, though plants then require both light and sun heat, yet the case is different; the sun’s rays have then much greater power, and it is found that their influence is sufficient, without at all times admitting them directly on the plants growing in these artificial atmospheres.

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The position of the Cucumber house, with reference to the ground line, must be determined by local circumstances; if the situation and sub-soil be dry, it may be carried below the surface in the manner represented in the annexed engraving, of which (a) is the ground line, (b) the pathway, and (c) the lowest point excavated: the same course may be adopted if the soil, though not naturally so dry as this, can be rendered so by thorough drainage; but when the ground does not admit of perfect drainage, the structure must be sufficiently elevated to avoid the risk of injury from the dampness of the locality.

The angle of elevation is not, as it is sometimes asserted to be, a point of indifference, though mathematical accuracy is certainly by no means required: in the annexed engraving, the angle of the roof is about 55°, this provides for the admission of the sun’s rays in the winter months, when his position is comparatively low in the horizon, to a much greater extent than could take place if a more ordinary slope were adopted. A still more elevated pitch would doubtless effect this object in a still more perfect manner; but would not be equally applicable to the requirements from a permanent structure, which would be wanted for summer as well as winter use.

A reference to the sketch, will at once shew the general nature of the internal arrangements. There should be a tank (d) supported by brick piers (p) in which a circulation of heated water would supply a genial warmth to the soil above, and to the roots of the plants growing in the soil; this tank should be heated by a small boiler, conveniently placed with reference to adjacent arrangements; a series of iron pipes (e) attached to the same boiler, would supply the requisite heat to the atmosphere. It may perhaps be thought that the application of the gutter system of heating would in this case be preferable; but as there would be a perfect command of moisture, as will be explained further on, it is desirable to have dry heat also, under controul, and this can be better effected by means of the pipes than by adopting the gutter plan of heating. I cannot in this place forbear protesting against the limited surface of piping generally employed in heating plant structures; what is thought to be just enough to maintain a given temperature, is usually after minute calculation, the quantity which is made use of, and the consequence is, that under adverse circumstances, the apparatus is necessarily worked at its highest pitch; and I believe that the application of heat in this form, whether it be by means of an hot water apparatus, or by a common flue, is most inimical to the plants submitted thereto. The admission of air, is a point which as far as I am aware, has never been effected in the manner represented in the sketch: it would be thus effected;—a series of apertures (f) should be provided at intervals along the front wall, which would externally be closed by small sliding shutters, and would communicate internally with a chamber (g) formed between the front wall and the side of the tank; this chamber would also communicate, by a series of openings, (h) with the interior space above the water in the tank, and from this space, through the covering of the tank, tubes (m), also placed at intervals, would be carried up through the soil, close to the side of the wall; these tubes should be furnished with caps or valves, so as so admit of the communication being stopped at any time. In applying this to the admission of air, we must not loose sight of a series of ventilators, (i), placed in the back wall of the house, which are of precisely the same nature and construction as the apertures (f), already spoken of. I shall have occasion hereafter, to notice the admission of air, but it will be well in this place, to explain the action of the plan proposed for that purpose: when it is judged that a change of the internal volume of air is requisite, the ventilators (i) are to be opened, which admits of a portion of the rarified air to pass off; the ventilators (f) are also to be opened, and by means of the action of these ventilators on each other, a portion of external air is taken in; this enters the chamber (g), which is warmed by its contiguity to the tank, and here becomes partially rarified, and rises to the top of the chamber; the apertures (h) admit it to the interior of the tank, where it becomes not only thoroughly warmed, but also imbibes a degree of moisture proportionate to the degree in which it becomes heated, and thence it enters the house by the tubes or shafts already spoken of. The advantages of warming and moistening the air thus admitted, are very important ones; for when either a cold or dry state, of the atmosphere prevails, its