158 
THE PHILOSOPHY AND USES OF BOTTOM-HEAT. 
and when, as generally occurs, the rays of the sun cannot reach that soil, it will 
often become so cold as to render the water administered in some degree stagnant 
and putrid, in spite of the best drahiage. 
The philosophy of bottom-heat, then, is, by making the soil in which plants are 
growing nearly as warm as the atmosphere, and by thus exciting the roots and 
keeping them growing as fast as the branches, to give a constant and healthy 
supply of nutriment to the latter, and so to promote the entire well-being of the plant. 
That such a practice is conformable , with the procedure of nature in the 
countries from whence our stove plants are derived, is perfectly clear. Vegetation 
there grows mostly in the rainy season, which is immediately succeeding the dry 
season. During the dry period, the earth is almost baked with heat, and thus, 
on the fall of rain, it becomes a literal hot-bed, sending forth a nearly incessant 
volume of vapour. Here, consequently^ is the natural method of furnishing 
bottom-heat. 
But the uses of a direct supply of heat to the roots of plants do not end with 
the excitation of the roots simultaneously with that of the branches. They are of 
a much more general and varied character. The soil, besides being thus made 
warm and genial, is prevented from holding too much water, and the practice is 
therefore a great auxiliary to drainage, which is one of the most influential agents 
in the culture of plants. With this perfection of drainage, too, there is a constantly 
attendant augmentation of fertility ; for a plant in soil through which fluids can 
circulate rapidly never loses its productiveness, when other circumstances are ahke 
propitious. 
Bottom-heat is further beneficial as afi'ording the means of guarding the roots 
of plants from the casual fierceness of a summer sun, of keeping them more 
uniformly moist, and of diffusing a delightful moisture through the atmosphere. 
We assume here, however, that the pots are plunged in the heating material, a 
practice which we consider inseparable from the system. Too frequently, in hot 
summers, when the sun is shining in all his fervour, his rays, falling on the sides 
of pots containing tender plants, speedily dry up the soil and injure the roots. 
This is avoided by the plunging attendant on the use of bottom-heat. By watering, 
likewise, the material in which the pots are plunged, as well as the soil within 
them, the moisture can penetrate the pots from without, and keep up a more 
equable supply, without the trouble of such oft-repeated waterings as are necessary 
in common circumstances. The same moisture, also, existing in the bed employed 
for plunging in, wall spread itself, by evaporation, through the air of the house, and 
so maintain it in a far purer, more favourable, and unfluctuating state, than water- 
ing the paths, flues, or hot- water pipes would do. 
We shall notice but one more benefit arising from the employment of bottom- 
heat, which is, that it hastens the development of the branches of plants in the early 
part of the season, by this means giving tliem more time to mature their shoots, 
and even itself contributing to the accomplishment of that end. It is the most 
