Dear Sib - Landscape gardening is a source of the highest pleasure to those who patronise it. Those who hold pleasure to be the result of mere accident, do landscape gardening a great injustice. Pleasure is the result of laws as fixed as those which produce heat and light, rest or motion. So, the more clearly the true principles of landscape gardening are understood, the more perfectly are we enabled to know bow they can be applied to the production of the highest degree of pleasure the art can afford.

Extensile gardens are being formed everywhere. The fund of pleasure their originators are laying up for themselves, will be great. That fond would be inflnitesimaly greater, if mere definite ideas of the sources of pleasure in gardening existed.

It has become very general for those who originate new gardens, to be their own landscape gardeners Were every one born an artist, any one might justly deem himself capable of laying out his own place in a manner capable of affording ultimately the highest pleasure; but it is not so. There are innumerable instances of gardens among the newer places, which afford no pleasure to any one, and which the proprietors themselves, feel to be a dead weight upon their enjoyments, and their purses, from no other cause than ignorance of the very alphabet of landscape gardening, in those who originally projected them. For a time they were interesting from their novelty, till, like the novelty of children's toys, they no longer pleased, and were eventually cast aside for other novelties, and became an incumbrance. In excuse or toleration of such misfortunes, it is often said that every roan derives most pleasure from "doing what he likes with his own " Any man might feel some pleasure in deciding to cut with his own hand, a " Greek Slave " in a block of marble, - but I guess that a more real, a more lasting, and more substantial pleasure, would ensue from the employment of the life-giving chisel of a high artist like Hiram PowErs, on the senseless block.

I am ashamed to make the comparison. It is ridiculous. Applied to landscape gardening it is more so. It is the work of a higher order of genius, to create a pleasing landscape in its generalities, and in its details, than to form a piece of sculpture of ordinary merit. Genius does not rule so proudly in poetry or music, drawing or painting, as she does in the art of landscape gardening. All other arts are content to imitate or represent nature - but landscape gardening has often to employ in her efforts, the aid of all other arts, and often to create even the very materials out of which she produces her happiest results. Gould any produce an equal to the beautiful landscape paintings of Claude Lorraine? If this be difficult, how much more difficult the aim of the landscape gardener, who has to produce in nature the superiors of the picture? It is difficult to arrange the scenes in a landscape painting, so as to give expression, character, and harmony, to each with the other, - but it is more difficult to arrange these in nature. In a picture, scenes, rarely corresponding - yet beautiful in their corrsepondence, can be brought and conjoined together with a fascinating effect. The imagination often, indeed, supplies the place of realities.

The landscape gardener has a more difficult task. He, too, must bring together, harmoniously and expressively, scenes too beautiful to be often seen in one whole, naturally. His imagination, too, must play, but far more cautiously, than that of the painter - because he has a higher and sterner tribunal to decide the value of his work, than the painter has. Nature deputizes to man her right to sit in judgment on the result of the painter's genius; on that of the landscape gardener she sits herself. Mankind have sympathies, give allowances, make extenuations; their knowledge of the constitution of nature is also limited - thus the painter has less to fear. Nature, herself, whose judgment the landscape gardener dares, judges his works according to the strictest letter of her law. Hence, if it he absurd for any mere amateur to paint his own pictures, under the impression that they would be perfect specimens of the art, it were decidedly more so in the case of one who deemed himself capable of laying out extensive grounds in the most perfect style of art, and consequently of obtaining as much pleasure from his garden as it might be capable of affording.

These gentlemen are at fault. They mar their own enjoyments. But they are not entirely to blame. There are so-called landscape gardeners, With whom everything must be this, or it is not natural - that, or it is not beautiful. Whatever stands in the way of this or that, must come down, must be torn away. This tree, that may have stood " a thousand years the battle and the breeze," must at last fall; that " mountain must be removed, and cast into the sea." Every thing must be levelled for the grade of their imagination, which cannot turn to the right or to the left, from the object before it. Few proprietors can stand this ordeal. Few could have the nerve of a Hamilton or a LIon, who could desire and effect the death of a Quercus peterophylla - the only known specimen in the world - for the poor equivalent of one more view of a bend of the beautiful Schuylkill - or of those who prefer the one or two year old silver maples, planted with mathematical precision by rule and square, in Penn Square, Philadelphia, to the noble trees that originally flourished there.

Landscape gardening, to be pleasing, must be accommodating. Nature herself, is so. In the plains she will give the Oak, the Beech, the Birch, a giant height and strength; on the hill sides and elevations she cheeks their luxuriance - while on the mountain summits she reduces them to the rank of mere bushes. They, therefore, who follow the " natural Style," may learn from this, that its results depend on their application of natural laws, rather than on any abstract formulas of lines or circles. Mankind generally run into extremes. Landscape gardening confirms this truth. The old system of squaring all walks, carrying them at right lines and angles, shearing and clipping every tree, and making everything so exactly correspondent, was so very absurd, that in the revulsion of ideas that followed its reformation, a line in any way, became an unpardonable offence against the new creed. And it is so to this day. Let it be the work of our generation to make extremes meet. Nature is not all lines or all circles. It is a beautiful mixture of both. The sun, earth, and celestial bodies are round, the dew-drops are round; the rivers and streams bend, and wind, and curve; the eye, the head, the limbs - all show forth in many a modification, cylindrical, bending, and sinuous forms.

But yet these are intimately connected with straight lines. The bold, determined looking curves which the branches of an old Tulip Poplar present, are beautiful; but the effect is considerably heightened by the tall and arrow-like straightness of the trunk which supports them; and gaze in admiration as We may, on the rounded symmetry, and curved proportions of some beautiful specimen of human kind, we cannot forget the linear lines, or longitudinal dimensions, that give relief, strength, and body to all the rest. Indeed, there is often beauty in a straight line, a beauty which nature frequently employs and glories in. It is her symbol of utility - it is the philosophy which she employs to show why she is beautiful. The idea of utility is always pleasing - it is diffused throughout all nature; the landscape gardener ought never to lose sight of this. Utility is the basis on which all ornament in nature rests. Whatever in art cannot be shown to be useful, is therefore nothing but extravagance. A perfectly straight line in gardening is useful; though entirely unadorned, would be more pleasing and more beautiful, than the most graceful curve would be without any useful object, either apparent or real.

It is but an one-sided view of nature that denounces the " Quaker-like straightness" of the streets of Philadelphia; but they arc beautiful because they are in character and in keeping with a place of labor and of business. There is no beauty in the idea of having to go round the circumference of a circle on a matter of business, instead of driving straght through its diameter, unless there can be beauty in an in convenience. Nor is it in reason that avenues should be denounced in all circumstances, or all occasions. They are often abominable, but sometimes grand. What could supply the want of the short wide avenue that leads from Walnut-street, Philadelphia, through the square, to the venerable old Hall of Independence? or who would object to the magnificent avenues of live oaks, a hundred years old, that adorn many of the fine plantations in Ca rolina.

It follows, then, that a curved line is not pleasing, merely because it is a curved line; nor is a straight line to be objected to, merely because of its straightness; either case will depend upon its being in character with its aim and purpose. It is the expression that governs the beautiful, and whatever is beautiful most be founded in nature. The landscape gardener has but to give a meaning, has but to stamp an expression of beauty upon his works; then, no matter whether his principles of design be circles, curves, or straightness - whether they be squares or triangles - whether his materials be foreign or indigenous, exotic or native, American or English - his works will please.

I again repeat my conviction, that many gentlemen do not employ professional talent in the laying out of their grounds, because they imagine that their own ideas, tastes, and views cannot be respected - that everything must bend to the exact principles on which the artist he might employ deemed " nature" to rest. Would it not be better to give up this pretension of following nature? Better to follow after nothing, or rather to imitate nothing, but to create for ourselves? It is folly to pretend that we can make our work appear to have been done by " nature herself." Let us avow our art. We value a picture because we know it is a picture, and not that we believe we are looking at something real; in like manner let us wish not merely to have our work valued because we have tried to " imitate nature," but because we have heightened the beauty of some portion of nature for ourselves. Thomas MErhan.

Bartram, near Philadelphia Jam. 10, 1352.