November and April." This is confirmed by several other persons who have enjoyed means of extended observation. The convenience of the wood-cutter will generally lead him to fell the forest in the early part of winter; and, probably, taking into consideration both the quality of the wood cut, and the welfare of the future forest, this may be best.

When the object is to destroy the growth, summer is universally declared to be the best season to fell a forest. As to the month, opinions differ. Many say, August, or late in summer; some say, June and July, or midsummer. Mr. A. C. Metcalfe, a very intelligent farmer of Lenox, says,-"In August, or when the tree has attained its full growth for that season." This seems to be the true period, at whatever time it takes place; when the wood is formed and before it has hardened, and the materials are laid up, in the trunk and root, for future growth. Mr. A. Bacon describes a conclusive experiment. "A gentleman residing in this vicinity, effected the clearing of a lot of young walnuts, (hickories,) oaks and birches, in the following manner. He commenced cutting about the first of March, and felled successive portions as he found leisure, till about the first of July. That portion which was cut between the 18th and 30th of June, was killed to the letter. Those which were cut before the leaves put forth, were most prompt in the renewal of their sprouts."

I find an opinion very generally expressed or implied, that every tree has a period of growth, maturity and decay. This is apparently hostile to the theory universally received by the vegetable physiologists, that the growth of every exogenous * tree, is, by its nature, indefinite. The discrepancy admits of being easily reconciled. Throughout Massachusetts, in the land left in forest, the soil is thin and poor. It will, therefore, in a comparatively short period of years, be exhausted of the nutriment essential to trees of any particular species. Every tree, like every other organized being, must perish when deprived of its necessary food. It is not surprising, therefore,

*All the common trees of our climate are exogenous, that is, they annually form a layer of new wood between the old wood and the bark.

that, in many soils, the trees should at last be unable to obtain sufficient nourishment, and should consequently thenceforward begin to cease to grow, and finally perish from inanition. We do not find this taking place on our rich intervales, and it might every where, probably, be prevented by supplies of fresh, nourishing soil. The proper inference, therefore, from the fact that trees are dying on the ground, is, that their appropriate nourishment is exhausted, and that, if the ground is to be continued in forest, it should be sown or planted with trees of some other kind.

This is clearly indicated by what is constantly going on in the forests, particularly the fact which I have already stated, and which is abundantly confirmed by my correspondents, that a forest of one kind is frequently succeeded by a spontaneous growth of trees of another kind. Mr. P. Sanderson, of East Whately, writes me, "There is an instance, on my farm, of spruce and hacmatack being succeeded by a spontaneous growth of maple wood." Mr. Metcalfe, of Lenox, says,-"A forest of beech and maple is now growing on my father's farm, where stumps of white pine and some of oak and chestnut, are very numerous and very large." Oaks and pines most frequently succeed each other. Mr. E. Swift, of Falmouth, writes,— "Many instances have occurred in this town, of pine lands having been cleared of the pine timber, which has been succeeded by a spontaneous growth of oak." J. H. Cobb, Esq., of Dedham, says,-"I have known pine succeeded by hard wood in several instances." Mr. S. Freeman, of Brewster, declares,-"I have known frequent instances, where a forest of oaks has been entirely cut down, and succeeded by a growth of pine, and vice versa." Mr. W. Bacon, of Richmond, writes,— "We have seen hemlock succeeded by white birch in cold places, and by hard maple in warm ones; beech succeeded by maple, elm, &c." I have many similar statements from all parts of the State. Indeed, the Hon. D. P. King, of Danvers, tells me that the fact is so universally admitted, that he is surprised at my asking the question.

This alternation is not, however, universal. In order that it

should take place, the woods must contain trees of various kinds sufficient to supply the whole surface with seed. When this is the case, a wood of one kind will usually be found full of little trees of other kinds. "Upon clearing off the old growth, the undergrowth, which has been kept from the sun, shoots up with astonishing rapidity." That portion of it which is most unlike the previous growth, finds plentiful nutriment, while the proper food of the previous forest has been exhausted, and the woods naturally change their aspect.

The forests, as has been stated, form or improve a soil. This they do by their annual deposit of leaves, and by rendering the ground accessible to air, by the action of their roots. Both operations are essential, and aid each other. If the leaves were not deposited, the surface of the ground would speedily become dry and hard, and the radicles which had previously pervaded it, would be exposed to cold in winter, and to heat and drought in summer. The covering of leaves protects against all. By them the superficial portions are kept moist and soft, and permeable by the delicate radicles, and these are protected, while they are made readily accessible to moisture from rain charged with carbonic acid, and to air and a tempered warmth. The covering of leaves thus secures all those circumstances which are most favorable to vegetable growth. It is, therefore, justly enumerated, by some of my correspondents, among the things most unfavorable to the growth of trees, to gather the leaves together, as is frequently done, either to burn them or to add them to the compost heap. This is bad economy. It is double robbery. It is taking from the forest what belongs to it, and is almost essential to it, and it is spreading, with loss of time, upon the present cornfield, what, left undisturbed, is at once a storehouse and laboratory of manure for the future cornfield, on which it is already spread and spreading itself.

The other circumstances enumerated as particularly unfavorable to the growth of trees, are browsing, pruning, a thin soil, exposure to sea breezes, to high winds, and to frosts.

* Mr. A. Bacon, of Natick.

The first of these, completely within the control of the forester, is the browsing of cattle. This is highly injurious to a forest in every state. It is destructive to the young trees, to the lower branches of taller trees, and to the undergrowth, which, in an old forest, is the hope of the future. Sheep and horses are not less injurious than cattle. All should be entirely excluded from woodlands intended to be valuable as such, and to renew themselves.*

I have already spoken of pruning. Where the object is wood, it may be doubted whether any pruning is advisable, except in the case that a branch of one tree materially interferes with the growth of another. Plants receive food by their roots, and digest and convert it to their various products, by and in their leaves. Both roots and leaves should therefore be left to extend and expand themselves as freely as possible; the one to occupy all the space just below the surface of the ground, the other to gain all the air and light within their reach above. Whatever checks this free expansion, has a tendency to lessen the product of wood.

On thin soil the roots cannot penetrate far, and a tree, surrounded by others, will soon exhaust the proper nutriment within its circle, and must then begin to fail. As soon as this happens, it must be removed, and trees of other families must be sown or planted in its stead. The proper treatment for thin soils, is, therefore, a rapid alternation of crops.

ence.

Most forest trees are injuriously affected by the sea-breeze, and we generally find them stunted and dwarfed by its influThe remedy is to plant numerously the hardiest trees along the seaward border. Those that most successfully resist the sea-breeze, are the sycamore or plane tree, the linden, the poplars, particularly the balm of Gilead, and many of the pines. Almost all trees may do it when growing in large masses.

Where a forest is to be renewed artificially, and where the trees are out of the reach of cattle, there is no objection to their grazing among them. One considerable recommendation of the Duke of Athol's mode of redeeming lands by planting larches, is, that the ground is improved for pasturage by the growth of grass under the shade of the trees.

The effect will then be less and less,-rapidly diminishing as you recede from the sea. On the capes and headlands projecting into the Atlantic, along the coast of Massachusetts and Maine, and exposed to the terrible northeast winds, the undisturbed original forests, when half a mile wide, have in the middle as large trees as are due to their depth of soil.

It is often very difficult to make trees begin to grow near the sea; sometimes it is impossible, without protection. But a low wall of loose stones, seaward, is sufficient to protect young trees near it until they get a little higher than the wall. The successive rows inland will be better and better protected, and will rise each higher than the preceding; until, at the distance of a few rods, they may rise to a tolerable height. When a belt of trees is once established, in such a situation, it should be kept undisturbed as long as it will serve the purpose of protecting the trees within, though it may be of no other value.

A course altogether similar should be taken in planting a much exposed hill. By beginning at the bottom and gradually planting upwards, the top may at last be clothed; as every belt of trees of a few feet in height, will protect a younger one a little higher on the hill.

Wherever trees are planted for use in the arts, it is important to give them the most rapid growth possible. Of wood growing on the same soil, that which grows most rapidly is strongest. That of which the circles of growth are narrowest is also weakest.* This fact is familiarly known to ship-builders, makers of lasts and of trenails, and of all those articles which require great strength. The reason is obvious. The circles of annual growth are separated by zones of loose, porous structure and inferior strength.

The strength of wood is proportioned to its weight. And as

* Buffon, II., 307. A circle of wood is annually formed on the trunk of a tree, between the outer previous circles and the inner bark. The space intervening between the annual circles or layers, is loose and porous, and contains very little solid substance or strength. The more frequently, therefore, these weak spaces succeed each other in a given thickness of wood the less must be the solidity and strength of the wood.