164 



CASSELL'S POPDLAE GAEDENING. 



dagrees more. The daily temperature should not 

 rise more than from five to ten degrees higher with 

 fire-heat. From November to February the plant-stove 

 should also range from five to ten degrees lower than 

 from February to October. During the latter periods 

 from 80° to 90° sun-heat, for a few hours in the 

 evening, wiU not injure these houses. As the light 

 gains in intensity, the temperature may be safely in- 

 creased in proportion. 



Temperature of Orch.id-liouses.— Where 



these are numerous, at least three ranges of tempera- 

 ture are maintained, the hottest ranging from 65° to 

 70° in winter to 75° to 90° in summer; the second 

 from 60° to 65° in winter to 65° to 75° in siunmer; 

 and the third, or cool Orchid-houses, from 45° to 50° 

 in winter to 55° to 65° in summer. 



Heating. — This will be treated separately, in so 

 far as boilers, pipes, furnaces, the arrangement of 

 heating materials, &c., is concerned, ^nly the 

 practical use of heating machinery in the every- 

 day business of keeping up the heat, as it is 

 called, will be adverted to in this place. This of 

 itself, however, is a large subject, and embraces the 

 economical use of fuel, as well as its timely consump- 

 tion to the best advantage ; in a word, the whole art 

 of stoking — an art less understood and more wastef ully 

 practised than any other within the entire range of 

 horticulture. Two sources of waste and mischief wiU 

 be noticed. The first is the piling up of fresh fuel 

 under the base of the boiler, and the second the 

 banking up of fires during the day. The first does 

 its best to keep the boiler cool, and bum out the 

 furnace-bars with the intensity of the heat wasted. 

 This practice often originates from having the fur. 

 naee too short and too deep. All furnaces should 

 have a dead-plate, a foot or two feet in length, between 

 the furnace doors and the bars. On this plate the 

 greater part of the charge of fuel should be laid ; there 

 it would be partially charred, and the flame and 

 gases from the coal pass along under the boiler, and 

 between its crown and the glowing embers beneath, 

 adding immensely to the heat. 



The first act of good stoking consists in pushing all 

 the half-consumed fuel under the boiler, to become 

 glowing embers in turn, then place a fresh charge of 

 cold, raw fuel, on the plate, to succeed in due course 

 that removed. There used to be a boiler with a 

 second sloping plate — Kewley's patent — that 

 lengthened the space for fresh fuel — and proved to 

 some extent self-acting, by sloping down the par- 

 tially decomposed coal on to the furnace bars below. 

 The saving of heat by such modes of stoking is most 

 inadec[uately measured by the saving of coal. On 

 the contrary, that is the smallest part of it. The 



greatest saving is effected by the fact that by this 

 simple mode of stoking each pound of coal gets at its 

 work in glowing condition, so that its whole force is 

 expended on the warming surface. 



BanMng Up.— A certain amount of banking 

 up at night is a necessity. Unless stokers are 

 to sit up all night, it is needful to mix bufiers 

 to pure coal, or other fuel (in the form of ash, 

 clay, or chalk), as these check the fierceness of com- 

 bustion, and make a fire hold out till the morn- 

 ing. Much of this, however, involves a, prodigal 

 waste of heat. Combustion might be equally well 

 checked by moderating the draught up the chimney 

 through shutting out most of the air, while the 

 furnace would be full of glowing fire, instead of 

 cold, inert ashes. But the evUs of night bank- 

 ing are small compared with the day damping of 

 fires. These have a provoking tendency to break 

 through the inert blocks just when the heat is least 

 needed (that is, when the sun is at its hottest), the 

 pipes will often be found to match, and the result 

 of the meeting of the two heats, as practical men 

 put it, is most disastrous. The only safe way, and 

 it would save often half the coal consumed, is to 

 insist on no day damping up of fires from April to 

 October. During that period, when there is a 

 prospect of a bright day, the fires should be raked 

 out at 7 a.m. By keeping a stock of kindling 

 lying at hand it is easy to relight them should a 

 change of weather occur, and the labour and trouble 

 are nothing to the coal saved, and the insect and 

 other evils averted from the plants. 



By careful attention to these two points daily, the 

 most heat would be got out of the coal, a regular 

 temperature maintained, and all possibilit}' of a most 

 injurious mixture of solar and fire-heat, and con- 

 secLuent excess, avoided. 



Damping Down. — The use of artificial heat 

 almost involves the necessity of this practice, which 

 is one of the most important dfiily routines in plant- 

 houses. It is a common saying that artificial heat 

 dries the atmosphere. Some advocated fines on 

 this account, and others condemned them for over- 

 drying. One of the prejudices against hot- water pipes 

 at first was, that they would make the air too moist. 

 This was soon found to be a mistake. Excepting 

 for the small modicum of heat absorbed by the 

 bricks or tiles of flues, they dried the air no more 

 than hot-water pipes, which are as impervious as 

 they are non-absorbent. But all heat added to the 

 air strengthens its capacity for moistiu^e. Hence 

 the more heat, the more moisture absorbed, and 

 the larger the supplies needed to keep the air of 

 plant-stoves and Orchid -houses sufficiently moist. 



