294 Modern Improvements in Horticulture, 



Climate. — To protect plants from the cold of winter is so 

 habitual to the British gardener, that there is no room for addi- 

 tional circumspection on this score ; that defence should be com- 

 plete, is evident ; all buildings for this purpose should in their 

 construction admit of every degree of heat artificially applied, 

 which in extreme cases may be necessary. A house-frame, 

 or mat covering, should be equally capable of repelling frost at 

 zero of the thermometer, as it is when only at the thirty-second 

 degree ; many houses are imperfect in this respect, and, owing 

 to badly constructed flues, or want of sufficient fire-places, the 

 crops or plants are lost, or placed in jeopardy. It has often 

 occurred to the writer, that admitting supplies of air from wells 

 and other deep excavations in the earth, would be a cheap and 

 effectual security against the hardest degree of frost ;* and even 

 in summer, admitting the temperate and moist air from such 

 subterranean cavities, would be far more suitable and refresh- 

 ing to plants than the highly desiccating air, under the influ- 

 ence of a noon-day sun : for who, acquainted with what hap- 

 pens in a hot-house in a hot day, but must wish at the time he 

 could mitigate the parching effects of the united direct rays of 

 the sun, and the reflected and accumulated heat from the glass 

 and form of the house ? This is only counteracted by copious 

 waterings within the house, and by shading : — the first, from 

 increased evaporation, generates cold, or (properly speaking) 

 a lower degree of heat, (but which increases the heat because 

 it is first raised as steam,) so that from this union of extreme 

 heat and humidity, the plants are, for a time, actually stewed ! 

 and, though apparently refreshed, it is a degree of excitement 

 which they should be but seldom subjected to. Thus it is ob- 

 vious that the light and heat of the sun must be guarded against 

 as well as the consequences of too low a temperature of heat ; 

 and that means for shading plants in our system of forcing in 

 summer are as necessaiy as defending them from the rigour 

 of winter. 



Soils. — ^The surface of the earth is composed of different 

 qualities, more or less suitable to all vegetable products : as 

 sand, clay, bog, or gravel, and of these there are numberless 



* Such subterranean chambers would be found highly useful^ o r many purposes 

 of gardening, beside that of supplying warm air. 



