1127. The amelioration of climate is advantageous, in improving the qualities of vegetables, by increasing or diminishing its temperature according to the nature of the plant; unless, indeed, it be situated in a climate which experience and observation show to he exactly suited to its nature. Hence the origin of shelter and shade, by means of walls, hedges, or strips of plantation; of sloping surfaces or banks, to receive more directly or indirectly the rays of the sun ; of soils better calculated to absorb and retain heat; walls fully exposed to the south, or to the north; of training or spreading out the branches of trees on those walls; of hot-walls; of hot-beds; and, finally, of all the variety of hot-houses. Nature also suggests this part of culture, by presenting, in every country, different degrees of shelter, shade, and surface, and in every zone different climates.
