196. The Chesnut-tree (Fagus castanea, L.; or Castanca vesca of Brown; Moncecia Polyandria ; ?lmentacece, Juss.) is considered as a native of the southern parts of England, where, at any rate, it has long been naturalized. It has a place in zt English Botany," t. 886. It is not much culti vated for its fruit in this country. As a forest-tree it is well known, though perhaps scarcely duly prized. The variety preferred is called the Spanish chestnut. It may be 'proper to observe, that when fruit is the object, graftect trees should be resorted to. The grafting of chestnut trees has long been practised in Devonshire, and it is now likely to become general. The stocks may be raised from the common nuts, but the grafts are to be taken from bear ing branches of such trees as yield the largest and fairest fruit. The timber of these grafted trees is of little value; indeed the tree generally continues in a dwarf state : but the fruit is not only sooner produced, but is of better qua lity and more abundant. The nuts are not so large as those imported from Spain ; but they are more sweet: They may be kept in earthenware jars, in a cellar somewhat damp, or covered with earth or sand, in the manner recom mended for walnuts. The French call these grafted trees marroniers ; and the forest trees, chataigniers. The•chest nut is suited to the same kind of situations as the walnut tree above spoken of.
197. The chinyuapine, or dwarf Virginia chestnut, (Fa gus pumila, L.) has long been known in English gardens; but the fruit is small, and has not been much attended to.
198. In this country, even in ordinary- seasons, several of the fruits which have now been treated of, such as the grape, the peach and nectarine, and the fig, and more par ticularly the finer varieties of these, are found to be brought to greater perfection, or the trees are more effectually kept in a healthy and fruitful state, by having recourse to a cer tain degree of artificial heat. If this be true in the south of England, much more may it be affirmed of all that part of the island which lies to the north of York. Glazed houses, under various names, have therefore been contriv ed for the purpose or forwarding and defending the blos som of the trees, and the setting of the fruit, in the spring, and for ripening the bearing wood for next year in the au tumn, the maturation of the fruit itself, at least in the case of peaches and nectarines, being left as much as possible to the influence of the sun and air. The vinery, the peach house, and the fig-house, ought not, in general, to be con sidered as forcing Mouses ; but as calculated rather to as sist the natural efforts of the plant, and to make up for the imperfections of the climate, every possible use being in the mean time made of the natural climate. They may, however, be converted into forcing houses, by varying the time of applying the artificial heat ; and in this way, not only cherries and strawberries, but grapes and peaches, may be obtained many weeks before the natural season ar rives. The pine-apple, which has not yet been spoken of, requires continually an increased, and even high tempera ture ; while the orange tribe needs little more than to be saved from frost during winter,.
The disposition of hot-houses, in regard to the garden and pleasure grounds, has been already spoken of. A suite or range of glazed houses is generally formed together, with only glass partitions between them. In this case the green house is sometimes placed in the middle, and the stoves at each end, so that, during winter, a person may pass into either hot-house without opening a direct communication between it and the external air, which, on account of the rarefaction of the air within, is ready to rush in.
Hot-houses are comparatively of modern invention. They were unknown in the days of Gerarde and Parkinson, that is, of Elizabeth and James VI. After the civil wars, hor ticulture seems to have received more attention ; but a glazed house, with a furnace and flues, does not appear to have been constructed previous to 1684. Sir Hans Sloane,
writing in that year, mentions that Mr Watts, gardener at Chelsea Garden, then recently instituted, had a new con trivance for preserving tender exotic plants during winter: " he makes under the floor of his green-house a great fire plate, with grate, ash-hole, &c. and conveys the warmth through the whole house by tunnels, letting in upon occa sion the outward air by the windows." The green-house was thus converted into a stove, or made to answer the purpose of both. Separate houses for plants belonging to very warm climates were soon found to be necessary ; and in 1724, Bradley describes a stove, or conservatory, with flues and every thing in the manner of a modern dry stove. The bark stove was soon afterwards introduced ; the heat resulting from the fermentation of tanners bark being em ployed, however, in the culture of pine-apples before it was applied to ornamental plants of hot climates. Two kinds of stoves are at present in common use, the dry stove and the bark stove.
Dry Stove.
199. The dry stove is generally constructed with up right glass frames in front, and sloping glass frames by way of roof, extending perhaps to within four feet of the back wall of the house, which space of four feet is commonly covered with slates. The angle at which the glass is made to slope is usually about 35°. The floor is raised two feet above the exterior surface, in order to give room for the flues, which, if sunk low, do not draw freely. The flues are carried to the extremity of the house, and returned se veral times, according to the length and breadth of the building. They are constructed of fire-brick, and the co vering is composed of square tiles, about an inch and a half thick. In Scotland, where sandstone abounds, the co vers are usually formed of flags, two inches or somewhat more in thickness. The flagstones of the Hailes Quarry, near Edinburgh, are excellent for this purpose : the finer lamina: from the quarry at Carmylie, in Forfarshire, com monly called Arbroath pavement, are apt to crack and shi ver from exposure to heat. They are generally made about 18 inches deep, and of nearly equal breadth, and hor ticultural writers have in genet al recommended these di mensions; hut there can be little doubt that the breadth should be nearly double the depth. Mr Stevenson, civil engineer, founding on some experiments made in construct ing a drying-house, has strongly recommended this im provement. (Scottish Hort. Mem. i. 143. He observes, that " the flues in general use are of too small dimensions; there is riot capacity in them for allowing the heated parti cles of air to expand ; so that the heat passes rapidly through such narrow flues, and makes its escape with the smoke, in what may comparatively be called a latent state, without being allowed to act on a surface large enough to rob it of its caloric." Ile farther remarks, that an ment heated with flues of a wide, but shallow, form is less liable to sudden .changes of temperature, than where the flues arc small ; and that such flues possess the advantage of seldom or never requiring to be cleaned. The furnace is generally so situated, as that the upper part of the arch is as high as the top of the flue, where the heat is intro duced into the house. The height of the body of a fur nace, of the usual dimensions, is two feet four inches, va rying, however, according to the slope of the ground ; the width is nearly the same ; the length of it inside three feet; the door a foot square ; and the length of the back of the furnace two feet. In the dry stove a stand is erect ed for supporting shelves, on which the plants arc to be placed ; the stand and shelves together being called the stage. In this stove all kinds of succulent plants, such as cacti, mesembryanthema, stapelix, and aloes, are pre served, with many other tender plants which do not require bottom heat.