paliers of Sir Humphry Davy, or the experiment of Mr. Maher; for in this case, a great part of the usual supply of sap is prevented entering the depressed branches, and is driven into the next buds or branches that offer the most vertical channels, where it is expended in forming new shoots.

Likewise by ringing or depriving the base of a branch, of half or more of its bark, by which, as half of the vessels will be cut off, the supply of sap will be lessened.

And the same effect is produced by cutting short the long roots of a luxuriant growing tree.

On the principle, that the evaporation and inspissation of a fluid are determined by the extent of surface exposed to the action of heat, the preparation of the fluids, in a plant for fructification, appear to be governed. Thus, if a vessel be deprived of one half of its contents, the remaining half will be evaporated or inspissated in the same time that the whole would have been, if placed in a vessel exposing double the extent of surface.

As it appears that the food of vegetables consists of water holding certain substances in solution, and that all vegetables, and vegetable products, are composed of oxygene, hydrogene, carbon, and earth, in due proportions, and that vegetables, when exposed to the action of the sun, possess the power of expelling oxygene, we may suppose, that with this power they are enabled to arrange all the required proportions of their different elements, to compound their various matter.

to sustain health, that the grand machinery be preserved uninjured and complete; and in conformity with this, if we wish to limit the size or surface of a tree, we must withhold the food: this is the only check or restraint Nature will admit of.

That her great work of creation and propagation may not be obstructed and retarded in vegetables, by the accidental privations they are subject to, from being made subservient to the use of animals, Nature, all-bountiful in her provision, and ever fertile in resources, has given them the power within themselves, to a great extent, of repairing and retrieving their losses; and to this end, every plant and every branch is furnished with more buds, than are required for the immediate formation of branches or blossoms; so that if one be destroyed, another may be ready to take its place, and prevent a waste of time or surface: thus we find that the efforts of a plant, from the seed forwards, are to attain and acquire the surface proportioned by its nature to the supply of food necessary to enable it to fructify and propagate its species; and until it has obtained this required extent, the juices by which it is sustained flow to the extremity of the leading branches.

In those trees which grow erect, the sap is always impelled forward in the most unobstructed and perpendicular channel until they attain a height proportioned to their situation; it there forms the head in a shape best calculated to present an uniform surface to the influence of the sun

and air, which is generally found to be conical or spherical; and that this may be effected, whenever a growing tree is curtailed in its branches, by the removal of any of them, the sap which those would otherwise have required is thrown into the remaining buds, in addition to what would have been their natural share; and they are in consequence increased proportionally in length and bulk, thus furnishing a surface equal to what the whole would have done, if suffered to remain.

In all plants there is a power of raising the sap, different to that of rarification or gravitation, which is evinced by the foregoing observations; and it has been the want of a due attention to this fact which has puzzled and confused all the different authors on the cultivation and management of fruit trees. In making their comparisons, therefore, and in forming their maxims of practice, I must request my readers will bear those observ. ations in mind.

GENERAL

OBSERVATIONS AND COMMENTS

ON THE ART OF PRUNING.

As most of the more valuable fruits, cultivated in this country, are the natives of a warmer climate, it has been found requisite to protect them from cold currents of air, and to assist them by an accumulation of heat; and as the means of effecting this are attended with great expense, it has ne cessarily led to the study and observance of the most advantageous and economical mode of culti vating and managing fruit trees, so as to enable them to flourish and produce the greatest quantity of fruit within a limited space or compass; and for this purpose they have been fixed to walls, frames, &c.; and the mode of conducting the process constitutes the Art of Pruning or training fruit trees, and forms the great object of the different authors I have quoted, which the following extracts will shew; and also how far their instructions are equal to the end in view.

The reader will perceive that most agree as to the value of certain effects, but fail in describing

any certain means for producing them with uniformity and success, from the want of a correct knowledge of the cause.

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Bradley, in his general observations, says, have taken notice in this and my other writings, that while the juices of plants are green and undigested, such plants shoot vigorously into large branches without any show of bearing fruit; but, on the contrary, when the sap of a plant becomes more ripened and sedate, that plant will produce smaller shoots, which will set for blowing or fruitbearing.

"As to the consistency of the juices in the vigorous shooting plants, and in the slow shooters, or those which are come to fruit-bearing, it is in the first like the most fluid liquid, in comparison with the second, which is more dense or thick, as if it had gum mixed with it; when, therefore, we observe vigorous growing plants, and the reverse of them, we may know that the juices required to render a plant fruitful must be of a less active nature. I am more particular on this head, because it is impossible for any one to prune a tree with any tolerable success, unless he has regard to these considerations."

So far this author is correct in his observations of the effect; but as to the cause, his conclusions are abstruse and erroneous.

He further says, "This however must be always considered with my doctrine of the circulation of sap in plants, whereby it appears, that when any

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