Fig. 2. displays the manner in 'which the flues are made to meander through the several benches, between which the vals should be filled up, to within two feet of their tops ; thereby to allow the means of shifting, watering, or the whole may be built up as in fig. 5. provided their joint breadths do not exceed three, or three and a half feet ; if more, they would clude the possibility of giving the due to each individually. The squareblack spaces, under each bench, shows the passages of the flues, the sides being half a brick in thickness, and the tops covered only with a strong tile, well ce mented down, and plastered over. By this means any part of the flues can be easily cleaned or repaired. Our readers will of course understand, that where any part of the hot-house is thus benched, it need not be excavated, that mode being only requisite for the lodgment of the tan in the parts intended for keeping up the heat by immersion of the pots in the hot beds.
The average heat of the interior should be from about 75 to 80 degrees ; but at particular critical times, when pines, &c. require much forcing, it may be carried np to full 85, or even to 90 degrees, so as to correspond with the temperature of their natural climate. It is remarkable, that in those places where pines grow wild, they possess the highest flavour, far exceeding that of the domesticated fruit, and that they ordinarily undergo a change of about 12 or 15 degrees between the average heats in the shady parts, where they grow, at mid-day, and at mid-night. Yet our gardeners keep them full as warm during the night, during the day. Perhaps some assiduous and curious spe culator in this branch of horticulture May deem the above hint worthy of notice. The entrance into a hot-house should always be by means of a small anti-cham ber, shutting very close ; for when a door opens abruptly, so as to admit the exter nal air, those plants which are contiguous thereto will receive a shock from the cold air,thus inevitably allowed to reach them, and will be far less luxuriant than others of the same kind, which, by a more for tunate locality, escape the baneful in fluence. We would recommend the sketch given in fig. 4, to the attention of our readers ; in it A is the anti-chamber to the hot-house B,and C is the fire-place,whence the chimney forms the several flues that pass under the benches, and through the back wall D, C ending in the chimney E.
It will be found most convenient to have the door in the centre of one end of the hot-house, and as that part will necessarily he raised by the slope of the surface of the beds and benches, four or five steps may he made, either in the anti-chamber, or in the hot-house. It will also be found useful to make in the back wall various small apertures, one for each binn, that the old tan, which has lost its heat, may be re 'moved from below by means of scoops and hoes; the surface of the binn being, in the meanwhile, covered with bass-mats,straw, &c., to exclude the external air. When
the old tan has all been removed, the aperture should be closed, and the fresh tan be filled into the binn by two men,with a long narrow basket, which might be ad vantageously rolled up the path-way or alley, between the binns and the bench es, on a small truck frame.
In small hot-houses, such as we some times see in the gardens attached to little country-boxes, the heat might be cir culated from a kitchen fire, provided the benches were raised sufficiently high to receive that benefit without affecting the draught. This would, in many instances, be found convenient and economical. In such the air might be admitted, merely by having one or two panes of glass set in metal frames, to be opened on hinges, as we often see in places where sash win dows would not answer, or where only a slight change of air is needful.
We shall conclude this article with re marking that hot-houses require conside rable attention, and are extremely expen sive, both in their construction. and in their support. A thermometer should al ways be suspended in some shady part and, in warm weather especially, it will be found extremely convenient to have tin ventilators set in the sides, near the tops, as shown in the figure ; their action might at any time be stopped, by putting on a tin cap or cover, or by a sliding board; the latter would prove most con venient.
During the day time, in the summer season, the fires may frequently be al lowed to go out ; but so soon as the even ing chill is felt, the glasses ought to be closed, and the flues to be heated. As, however, some plants require more air than others, we offer to the consideration of our horticultural readers, whether a perpendicular glazed frame, dividing the hothouse longitudinally into two distinct parts, the front one to be kept partially opened, and the back one completely clos ed, would not be an improvement in the construction of this species of buildings. This might be so contrived as more ef fectually to guard against the sudden ac cess of cold air, and serve as an auxiliary to the precaution already suggested, of having the entrance guarded by means of an antechamber. The manner of attend ing to the plants in hot-houses will be seen under the head of GARDENING, where we have endeavoured to furnish a complete, but concise essay and calendar, and in which every matter of utility, of ornament, and of luxury, has been allow ed its due notice.