HOT-HOUSE. HYSSOP. 163 



bed are often protected by bundles of straw or fagots, 

 which tend to prevent the escape of the heat." Encyc. of 

 Gardening. 



HOT-HOUSE. " A hot-house is a building intended 

 to form a habitation for vegetables ; either for such exotic 

 plants as will not grow in the open air of the country 

 where the building is erected, or for such indigenous and 

 acclimated plants as it is desired to force or excite into 

 a state of vegetation, or accelerate their maturation at an 

 extraordinary season. 



" Such heat as is required, in addition to that of the sun, 

 is most generally produced by the ignition of carbonaceous 

 materials, which heat the air of the house, either directly, 

 when hot embers of wood are left in a furnace or stove, 

 placed within the house, as in Sweden or Russia; mediate- 

 ly, as when smoke and heated air, from or passing through 

 ignited fuel, is made to circuh'te in flues; orindirectly,-when 

 ignited fuel is applied to boil water, and the hot vapour, or 

 water itself, is impelled through tubes of metal or other 

 conductors, and either to heat the air of the house at once, 

 as in most cases, or to heat masses of brick-work, sand, 

 gravel, rubble, or earth, tan, or even water, (Hort. Trans. 

 vol. jii.,) which materials may afterwards give out the heat 

 so acquired slowly to the atmosphere of the house. But 

 heat is also occasionally supplied from fermenting vegeta- 

 ble substances, as dung, tan, leaves, weeds, &c., applied 

 either beneath 'or around the whole or a part of the house, 

 or placed in a body within it." Encyc. of Gardening. 



Steam affords the most simple and effectual mode of 

 heating hot-houses, and indeed large bodies of air in any 

 building, and is the most convenient carrier of heat, which 

 human ingenuity has ever discovered or employed. See 

 Encyc. of Gardening, from p. 310 to pp. 333, 502, &c. 



HYSSOP. Hyssopus officinalis. This is a hardy plant, 

 a native of the south of Europe, and grows to the height 

 of about eighteen inches. 



Propagation and culture. " It is raised by slips and cut- 

 tings of the branches, and by slips of the root and top 

 together. It likes a dry and sandy soil. When it is piopa- 

 gated by seed, sow in March or April a small poitioii. 

 either broad-cast and raked in, or in small drills, six inches 

 apart. The plants may mostly be transplanted into final 

 beds in June or July, nine inches apart, or some may be 

 Ranted as an edging ; or you may also sow some seed for 

 aii.edgiag, to remain where sown. Give the edgings oeca* 



