534 PRACTICE OF GARDENING. Part III. 



2866. Decayed leaves make good manure ; whereas, rotten tan is experimentally found to be of no value. 

 I have often tried it both on sand and clay, also on wet and dry lands, and never could discover, in any of 

 my experiments, that it deserved the name of a manure ; whereas, decayed leaves are the richest, and 

 of all others, the most suitable for a garden. But this must only be understood of leaves after they 

 have undergone their fermentation, which reduces them to a true vegetable mould, in which we experi- 

 mentally know that the food of plants is contained. This black mould is, of all others, the most proper to 

 mix with compost-earth, and I use it in general for pines, and almost for all plants that grow in pots : for 

 flowers it is most excellent. The remainder of this vegetable mould may be employed in manuring the 

 compartments of the kitchen-garden, for which purpose it is highly useful. 



2867. Leaves mixed with dung make excellent hot-beds ; and beds compounded in 

 this manner, preserve their heat much longer than when made entirely with dung. In 

 both cases, the application of leaves will be a considerable saving of dung, a circum- 

 stance very agreeable, as it will be the means of preventing the contests frequently 

 observed in large families, between the superintendent of the garden, and the directors 

 of the husbandry. 



2868. Steam as a bottom heat, Speechly observes, " seems to stand forward among the 

 modern improvements of gardening." Speechly knew, in 1796, only two instances in 

 which steam was applied as bottom heat ; and, with M'Phail, does not think it will 

 finally answer as a substitute for tan. Instances in which it is adopted, are now much 

 more numerous ; but time sufficient has not elapsed, and the opinions of gardeners are 

 yet too unsettled on its merits to enable us to recommend it for adoption in general 

 practice. For heating the atmosphere of hot-houses, there seems little (or at least much 

 less) doubt of its being preferable to fire-heat. 



2869. Gunter, of Earl's Court, tried the application of steam as a bottom heat, by introducing the vapor 

 into a chamber in the bottom of the pit, over which were laid cross bars covered with brush-wood, and, in 

 some places, oak-planks, pierced with holes. On these the mould was placed in which the pines were 

 planted. The quantity of heat imparted to the earth was very great, but, contrary to his expectation, no 

 vapor ascended into the mould, which became excessively dry and husky ; nor was he able, by frequent 

 waterings, to keep it in a state fit for vegetation ; the roots of the plants in it, in spite of every precaution, 

 becoming shrivelled and dry. (Hort. Trans, iv. 408.) 



2870. J. Hay, of Edinburgh, gives three examples (Caled. Mem. voL iii.) of steam having been adopted as a 

 bottom heat in Scotland. It is there introduced under vaulted pits, or chambers covered with rafters and 

 slates laid close in mortar, and has been found to succeed. (Different Modes of cultivating the Pine 

 Apple, &c. 174.) 



2871. Hot water as a bottom heat. Count Zubow, at St. Petersburg, employed steam 

 to heat a pit or cistern of water, over which, at about three inches' distance, a frame, 

 covered with faggots, was placed, and on this was laid the earth, in which his pines and 

 other exotics were planted without being in pots. The plan is said to have succeeded, 

 and a wholesome temperature to have been obtained and communicated to the mould 

 above the faggots. (Fischer, in Hort. Trans, iii. 430.) 



2872. Fire-heat. Recourse must be had to the furnace whenever the temperature of 

 the house, from the natural heat of the season, aided by the bark-pit, falls below 60°. 

 At 55° the decline of atmospheric heat will not be got so far as to hurt pines and stove- 

 plants in general ; but, if you light no fires till the thermometer fall to 55°, it may 

 happen that, before the flues can be brought into full action to affect the house, a 

 sudden retrocession in the natural season may sink the air at once five or six degrees 

 lower — then, the tenderest exotics will be in a hazardous situation. It is not advisable 

 to expose a plant that has been lately potted even to the extreme, 55°, lest it should be 

 checked in making new roots. To refuse the aid of the furnace till the latest moment 

 will also restrain the gardener from admitting fresh air, in the meantime, so as to have 

 always pure air in the house. The maximum heat to be caused by fire alone in abso- 

 lute winter, is 68°. This should be thrown to the middle of days not enlivened by 

 sunshine ; also, to periods when the heat of the bark-bed is from any cause deficient. 

 The medium, 64°, for mere fire-heat, should be interposed on preparing to air the 

 house in the forenoon ; and in the evening, between three and eight. 



2873. Pit-coal is the best kind of fuel, mixed with cinders of the same, on account of 

 the duration of the fire and regularity of the heat : cinders are lasting in the next de- 

 gree : peat may be resorted to under a deficiency of either of the others ; it -will require 

 more attendance : wood blazes off so rapidly, that to maintain and regulate a furnace fed 

 by it is very troublesome. (Pr. G.) 



2874. Coal-dust, formed into bricks, with one third of its bulk of clay or pond-mud, 

 has been tried by Knight. With these he found he could sustain a high and regular tem- 

 perature in his pinery with little expense or trouble, and that the burnt clay and ashes 

 were valuable as manure. (Hort. Trans, iv. 156.) 



2875. Time of the day for lighting fires. As soon as fires become necessary, Aber- 

 crombie says, " the attendant on the furnace should set it at work every afternoon, at 

 five, four, or three o'clock, according to the time of year, beginning an hour before sun- 

 set. His last examination of the furnace for the evening should not be earlier than ten 

 o'clock, when as much fuel should be added as will support the proper heat till the 

 morning, while the front of the fire is smothered with ashes to prevent too consuming a 

 draught. He ought to be again at the fire, to refresh it with fuel in the morning, within 



