SPECULATIVE IDEAS ON FORCING. 
23 
degrees in advance of the average atmospheric temperature. Such piping might he crossed by wide 
slates, and on these a foot deep of cinder-ashes might he levelled, or more if need be, to plunge in,— 
for plunging I would make a sine qua non. Under such circumstances, it is probable that a fire for a 
few hours, twice a-week, would suffice in ordinary seasons. 
Such a plan properly established would, if I mistake not, be in very frequent request; and as to 
fuel, as a very moderate, but certain amount of bottom heat would be required, the cinders from the 
other fire-holes would in the main suffice. For the purposes to which it would be applied, a bottom 
warmth, capable of a range from 55 to 65 degrees, would probably answer: for it would be principally 
wanted in autumn, commencing as soon as the natural ground-heat began to decline. 
Here, all the fruit trees, strawberries, &c., in tubs, boxes, pots, &c., might be plunged, as well as 
many things for the autumn and winter’s decoration of the plant houses, such as bulbs, roses, violets, 
pinks, lilies, American shrubs, rhododendrons, &c.; and if (as we have to suggest) a canvas or other 
skreen could be drawn over at night, to arrest radiation and ward off cooling winds, slight frosts, &c., 
a climate would be secured within just enough to keep the fluids slightly in motion. It must not be 
understood that the heat of the whole must be equal at all times. Plants thus thrown into a state of 
preparation for a late autumn or winter display, or for what is termed forcing, might be removed pro¬ 
gressively to their destination, whatever the structure or mode of heating, observing one thing, that for 
early fruits a continuation of bottom warmth would be most desirable. For retarded flowers, the or¬ 
dinary shelves would answer; for these in general have only to waste in blossom the stored-up energies 
of the preceding summer. The roots never having acquired an actually quiescent state, to say nothing 
of having been frozen, would be prepared to reciprocate with any circulation of fluids induced in the 
foliage or branches ; and it need hardly be suggested here that a thorough and harmonizing circulation 
of the fluids is of the utmost importance in all forcing, whether in the regions of Flora or Pomona. 
One thing should be taken into consideration by those who feel disposed to give a thought to these 
—it may be—hypothetical suggestions, which is the fact that the roots of plants in a state of nature are 
seldom liable to the great extremes of temperature to which the branch is subject—neither does it by 
any means appear that such was the design in their formation, and as evinced by the well known func¬ 
tions assignable to each. We do know that with regard to most trees, to say nothing of the ordinary 
perennial tribes, the branches, by an extremely low temperature during the winter, are thrown into 
what may be considered a state of rest. But what is the condition of the fibres during that period ?— 
the branches in perhaps an average temperature of some ten to twenty degrees of frost, whilst the 
soil at a foot deep or so indicating a temperature of about forty! Now, this is an enormous discre¬ 
pancy, and it may continue for weeks. Theory, as well as practice, has repeatedly pointed to the fact, 
that the fibres are anything but inactive. No! much has to be done—many tubes to be refilled—be¬ 
fore active vegetation can fairly commence, all this resulting from the perspiratory loss of the previous 
summer and autumn. Here, then, we seem to have a real principle ; and it remains for art to control 
adverse matters and to see that the principle is duly carried out. 
In considering this matter, the character of the autumnal atmosphere and autumnal light, as re¬ 
lated to the heat of that period, should be taken into consideration. It may, I think, be taken for 
granted that the conditions which ripen corn well are those which will tend to a fructiferous condition, 
as well as a free subsequent development in fruits and flowers. And what are these conditions ? 
Much remaining ground-heat, much light, and a very low temperature of air overhead—at least, in the 
night. Perhaps I have strained a parallelism in attempting to throw light on a subject hitherto 
rather obscure. The fact is, the question is, in a great degree, untrodden ground , and no wonder if the 
foot should slip in attempting to discover a track. My idea, however, of the use of an artificial bottom- 
heat is, that it should be more a guarantee against any sudden depression of ground-warmth, than a 
source of what is generally understood by bottom-heat. 
I before suggested a covering of canvas, or some other material, simply on the ground of preventing 
a too free radiation. Not that the branches would not endure the low temperature to which they might 
be subjected; but that extremes are in most cases best avoided. And moreover, in the case of things 
