to dispense with much of the labour, and all the filth, and the uncertainty which are consequent on the use of fermenting manure as a means of keeping up the temperature in which they are grown. In a small forcing house, besides these advantages being secured, all the operations of care and culture, can be performed just when they become necessary, without exposing the tender foliage of plants which have been submitted to an artificially elevated temperature, to the chilling influence of cold air, which is admitted whenever the sashes of an ordinary frame or of a pit, are opened, in order to bestow these necessary attentions. It may be urged that a dung bed has still the advantage, on the ground of economy; but when a fair calculation is made of labour and loss or anxiety on the one hand, and of duration on the other, such an assumption, will be quite untenable. Neatness, convenience, certainty, and economy, are the principal points of advantage which are gained by the adoption of pits heated by means of hot water, over those of a structure, depending for its supply of heat, on the aid of fermenting masses; whilst the attainment of a still greater degree both of convenience, and of certainty, which may be secured by cultivation in forcing houses, point out at once the advantages which render such houses, preferable to pits.

The application of the gutter system of heating, was not long since thought to be an improvement of great importance, and there can be no question but that it affords a means of regulating the moisture of the atmosphere of hothouses, in conjunction with the temperature, which prior to its introduction had not been attained; and as such, it is worthy of extensive adoption: it requires however some judgement in its adaptation to particular structures, and to render, it suitable, to effect any particular object for which it may be employed.

The tank system as a means of applying bottom heat, employed either in conjunction with the gutters, or with ordinary piping, to supply heat to the atmosphere, is the most important advance which has hitherto been made towards supplying the wants of those plants, which require such peculiar aid; and with reference to the Cucumber, it may be regarded as furnishing a new era in its cultivation.

The importance of bottom heat in the culture of tender plants, has always been well known by its practical effects. The mean temperature of the soil, at a slight distance below the surface, is universally above that of the superincumbent air; and consequently some degree of bottom heat is always supplied to plants, in a state of nature. Naturally, by means of subterraneous heat, and also by the absorption of the sun’s rays during the time they are forcibly directed towards the earth, it possesses the means whereby any material degree of cold at the roots of plants is prevented; and when the soil is acted on by the unveiled sun of an eastern sky, we cannot but feel certain, that even a considerable amount of heat must be experienced: hence arises the importance of taking advantage of every ray of sun which our climate affords, when the culture of the Cucumber, or of any native of warmer latitudes, is attempted out of doors in this country; and also of using every possibly available means of increasing rather than diminishing the temperature of the soil: and hence too, in forcing not only the Cucumber, but also every other plant which requires to be submitted to a confined atmosphere, and an elevated temperature, arises the necessity of providing such a degree of warmth at the root, as may tend to keep its vital powers in a vigorous state of action; it will effect this, by acting in conjunction with moisture, as a solvent of the food which is primarily contained in the soil in a solid form, but can only be taken up by the capillary action of the spongioles of the roots, when converted into a fluid state. The science of Chemistry has taught us that the ingredients composing the soil, act on, and dissolve, and combine with each other in various ways, sometimes being simply dissolved and held in solution, and at other times, entering into new combinations, and forming new compounds; but in all cases, the natural agents, heat and moisture, are necessary to produce these results, and to present to the tender roots of plants, food so duly prepared, as to be fit for their assimilation. Warmth in the soil, acts beneficially also, by preventing the sudden or undue interruption of the excitability of plants growing in it, which would be likely to result from the lowering of the temperature of the plants by evaporation, were it not for the action of the antagonist force, existing in and exercised by the heated soil, which heat, is communicated to, and absorbed by the plants.

It may be regarded as an established and universal rule, that all plants require the soil, and the atmosphere in which they are cultivated, to correspond with the natural circumstances under which they flourish; and as it has been repeatedly ascertained that the soil is naturally a degree or two above the temperature of the atmosphere, we have certain and unerring data for the application of bottom heat, and no more powerful evidence than this can be desired, to condemn at once the application of a very powerful degree of heat, at the roots of plants.

The importance of bottom heat in the culture of tender plants, being a practical fact established beyond question, another consideration arises as to the best means of producing it, and of regulating its application. Various substances and materials have been submitted to a process of fermentation, and so employed to effect it: stable manure, tanner’s bark, and the leaves of trees, are among the principal of these materials, and either of them will supply just what the plants require, as truly as these wants can be supplied by any other means; but from their very nature, they are violent, and fluctuating, and ephemeral in their action, and setting aside the labour which the employment of them necessarily involves, we have in these particulars, the special points in which the tank system of applying bottom heat far excels them: it is uniform, and constant, in its action; there need be no apprehension of the soil becoming overheated, for the source whence it derives its warmth ought never to boil; neither need there be any fear of its decline, or of a want of power, for when once thoroughly heated, a body of water will part with it in such a manner, that a very little attention to the fire, and a very little expenditure of fuel, will maintain its temperature for an almost incredible length of time; and as to power, it never should for a moment form a question, because a powerful degree of bottom heat ought never to be applied: a close attention for one or two hours during the twenty four which form a day, will maintain any apparatus in an effective state of action, if it is properly erected. How different is this, to what has been in days now past! when in rigorous weather, with the heat of his dung bed declining, the cultivator knew that at the peril of his crop, he scarcely dared to attempt to revive it, without involving a more serious because an accelerated evil; at any rate, if at an immense sacrifice of labour, his dung casings were replenished piece by piece, he knew too well, that often many days would elapse, before their action would be efficient and satisfactory, unless indeed an unlimited supply of materials, were in a constant state of preparation. By means of the tank, a fire could be lighted up, and the required effect produced in as many hours, as days would have been formerly required.

What has been already advanced, tends to the conclusion, that small forcing houses are preferable, and in the end more economical than pits and dung beds; and that the tank as a means of supplying