420 SCIENCE OF GARDENING. Part II. 



2187. Accelerating by housing, such as removing plants in pots and boxes, to sheds or 

 rooms in the night, and exposing them in fine weather to the sun, was practised by the 

 gardener of Tiberius, to procure early cucumbers ; and by those of Louis XIV. to force 

 peas. (Benard.) Parkinson and Gerarde describe the practice as applied to raising cu- 

 cumbers and melons in this country. 



2188. Accelerating by artificial heat in walls is a very frequent and useful practice. In 

 general it is accompanied by protecting-covers of canvass or netting (1495.) : but some 

 gardeners, as Trotter of Alva, a very high and exposed situation on the Ochill hills, never 

 cover their hot- walls ; but in ripening the wood in autumn, and in saving the blossom and 

 setting the fruit in spring, keep up such fires as will repel the frost, and evaporate the wet 

 that might fall on the wall. " No danger," Trotter observes, " is to be apprehended from 

 the severity of the spring months, even when exposed to all sorts of weather ; every 

 kind of covering being superseded by the genial heat of the wall." This he has long 

 experienced, even in England, but especially in Scotland, to be " the best preservative 

 of the blossom of young fruits." (Caled. Mem. vol. ii. 113.) 



2189. Accelerating by flued borders has been occasionally attempted, but can never 

 succeed by fire heat ; by tubes of steam, perhaps, something might be done, but the heat 

 can always be more economically applied by means of pits or frames, placed on raised 

 beds of mould, with arches, or some similar contrivance underneath. (See a description 

 of a flued border in Keil's Treatise on the Peach Tree, 8vo. 1780.) 



2190. Accelerating by covering with glass cases, of different sizes and descriptions, pro- 

 bably succeeded to housing. The Romans are supposed to have hastened the ripening of 

 grapes and peaches, by placing them under talc cases (55. ) ; and a French author, Be- 

 nard, informs us, that the origin of forcing the vine arose from one Gordon observing 

 that a shoot which had entered his room- window through a crevice, ripened its fruit some 

 time before those branches of the same tree which remained in the open air. The practice 

 of forcing peaches in Holland, is said to have originated from a gardener near Haarlem 

 putting hot-bed lights against his walls to ripen peaches in a bad season. By a mere 

 covering of glass, without any description of bottom heat, or any auxiliary mode of ac- 

 celeration, almost all fruits and flowers which grow in the open air in this country, may 

 be forwarded from one fortnight to one month, according to the season. Fruits may 

 by the facile means thus afforded of covering and protection, be retained in a ripe and 

 plump state from one to three months ; so that in general it may be observed, that 

 cold frames, as they are called, and mere glass cases, will double the ordinary time of 

 enjoying hardy fruits, and certainly they greatly increase the flavor of such as ripen 

 late, and especially of the vine and peach. 



2191. Accelerating by glass cases and artificial heat combined is effected by hot-beds, 

 pits, and hot-houses. 



2192. Accelerating by the common hot-bed is an ancient, general, but still somewhat pre- 

 carious and unmanageable mode. The heat being produced by a fermenting mass of ve- 

 getable matter, over which is placed the earth containing the plants, it becomes difficult 

 to regulate any excess of heat, and the plants are sometimes, in the empirical phrase, 

 burnt. When, however, the heat declines, it is readily renewed by linings or a sur- 

 rounding layer of dung. To remedy the defects of the common hot-bed, and prevent 

 the possibility of burning the plants, by interposing a stratum of air between the dung 

 and the mass of earth which contains them, is the object of the vaulted pit and M'Phail's 

 frame (figs. 230. 233.); to which there is no objection, but the greater original cost. 

 These structures actually save dung, and are more agreeable to the eye of those who 

 value order and neatness than dung-beds, 



2 1 93. Accelerating by means of walled j)its is very similar to that of forcing by hot-beds ; 

 with the advantages of having more room between the surface of the beds and the glass for 

 the tops of shrubs, and of the glass having a better slope ; but with the disadvantages of a 

 chance of burning in the first instance, and no power of increasing the bottom heat when 

 it once declines. Bark is generally used to lessen the first evil, as it does not ferment so 

 powerfully as dung, and the second is remedied by a surrounding flue. Such pits are 

 much used in all the branches of garden-culture. Henderson, of Brechin, proposes to 

 lay on the surface of beds of tan, or on hot-beds, pits, pineries, &c. fine drifted river or 

 sea sand, three inches deep. " This covering," he says, " possesses many advantages. 

 It will extirpate the slater or wood-louse (oniscus asellus), as the nature of the sand pre- 

 vents the insect from concealing itself from the rays of the sun. In dung hot-beds, it 

 keeps down the steam. To fruit, it affords a bed as warm and as dry as tiles or slates. 

 This covering also retains the moisture in the earth longer than any other, and is itself 

 sooner dry. It gives the houses a clean, neat appearance, and though it cannot be ex- 

 pected to remove the infection, where already introduced, will be found a powerful pre- 

 ventive of that great evil, mildew." 



2194. Accelerating by means of hot-houses is the master-piece of this branch of culture, 

 and is but of modern invention, being unknown till the end of the 17th century. Im- 



