The Gardeners' Chronicle and Agricultural Gazette . theheat of the sun, although great, is not increased byarlificial means as in glass-houses, where the tension ofthe atmosphere becomts immense; the young juicyfoliage is in consequence compelled to part with itsmoisture, and it withers in an hour. The admission ofair to lower the temperature, or rather to preventthe temperature from rising so very rapidly, is apoint too often overlooked, because it has not beenso clearly understood by those who build bouses forplants, as by those who grow plants in them. Almostall the great plant-structures w
The Gardeners' Chronicle and Agricultural Gazette . theheat of the sun, although great, is not increased byarlificial means as in glass-houses, where the tension ofthe atmosphere becomts immense; the young juicyfoliage is in consequence compelled to part with itsmoisture, and it withers in an hour. The admission ofair to lower the temperature, or rather to preventthe temperature from rising so very rapidly, is apoint too often overlooked, because it has not beenso clearly understood by those who build bouses forplants, as by those who grow plants in them. Almostall the great plant-structures with which I am acquaintedare notoriously deficient in this respect. Plate-glass andmetallic sash-burs offer little obstruclion to the admis-sion of light and heat transmitted from the sun, and onthis account, anomalous as it may appear, their value inhorticulture is estimated, and so it should be; becausethe watery juices of plants are elaborated just in propor-tion to the presence of them; but then they should bepresent naturally and In tropical countries, where vegetation is daily sub-jected to a vertical sun, plants are differently circum-stanced at the roots from those in our soil in which they grow becomes heated to an extentscarcely credible in this country ; so much so, that atseveral inches beneath the surface, 80° and 90° is no un-common indication of the temperature. How differentis the case in our large conservatories. Place, for ex-ample, a thermometer on the points of the branches inthe wood cut, and bury another in the soil about theroots, and this disparity will prove quite solar calorific transmissions in the tropics have a verydifferent influence on the earth from what the tempera-ture of a hothouse ever can have, even supposing theheat in the latter case to be much higher, and makingevery allowance for the natural tendency of bodies toassume an equilibrium of temperature when placed incontact with each other. No
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Keywords: ., bookcentury1800, bookdecade1840, bookidg, booksubjecthorticulture
