An ornamental road in any style of landscape embellishment is essentially a work of art, and should, under all conditions, express art in its design and construction. The dignity of a private place depends, in a great degree, upon the marked differences that should exist between its drives and the public highway; and although we should like to see the latter of a high standard, yet there is a degree of finish, keeping, and taste not requisite to its practical perfection. In the appointments of a well-kept estate, the roadways are quite important features; and considerations of tasteful as well as practical value suggest artistic design and location, and skillful construction and finish." In using the curved line in locating a road over natural grounds, we do not deny the character of art exhibited in the straight line, but consider its most appropriate place to be on those grounds treated in an artificial manner; nor do we propose to discard its use entirely in any school of landscape embellishment. It is of value in blending natural scenery with the architectural lines of the house, in uniting abrupt curves, and in such situations as the curved line would appear meaningless.

The general use of the curved line in natural landscape treatment is the most appropriate, and by far the most beautiful and graceful of all lines. It possesses, in a greater degree, the three qualifications of utility, economy, and ornament, and has no arbitrary conditions in its location. Two points decide at once the entire position of a straight line, while a curved line may pass through an infinitude of points, and be adapted to all positions necessary to display attractions or avoid objections.

Infinite beauty in a curved line suggests the use of natural curves; the theory of motion points them out, and every natural example of the beautiful combines them. The most graceful and elegant forms of the material world are described or bounded by curved lines; there is no higher form of beauty than that expressed by them, andl the effect is lessened by using lines of a different character. This is fully illustrated in nature; and from nature is elaborated the two forms of natural landscape adornment, the beautiful and the picturesque.

From this argument we propose to draw two conclusions, the first of which is, that natural curves, or, in plainer English, mathematical curves, are those only embraced in the field of absolute beauty; and the second is, the extraordinary facility with which they can be laid out, a certain, positive, truthful beauty at the minimum of expense. Every ordinary practitioner has some sort of a plan of his own, but so wonderfully gifted (?) is he with the art of landscape gardening, "that you might as well ask for a receipt to become a poet" as to expect him to impart the manner by which he finds a result. If he will work under inspection, his deficiencies can be easily recognized; his natural gift is ignorance, and its natural effect is costly.

The system, or rather no system at all, of laying out curves by the eye only, is the resort of the experimental tyro, and to those who care only for practical results, and nothing for cost, they will answer every purpose; but to produce a line of grace and beauty that is perfect in these requisites, that can be expeditiously done, requiring the least amount of time, and the most economy of means, something besides guess work, experiments, and opinions, must be adopted.

The ordinary gardener, in laying out a road, is not satisfied until he has apparently reached a mathematical curve. From every point of observation, forward and backward, he ranges his stakes in search of a true curve, and, finally, with repeated changes, he hesitatingly accepts a line that he thinks will do, and to which he returns again and again with a fresh eye to reconsider, as if a lingering doubt existed of some inaccuracies. An accomplished expert may use this plan successfully on level ground, but on uneven or undulating surfaces the eye can not be trusted. Thus a perfectly straight line drawn diagonally across a valley, appears to be curved, and a true circular curve laid over a broken surface, apparently partakes of its nature.. Optical delusions are every-day matters, and the eye differs in flat, rolling, hilly, and mountainous scenery. Shadows, foreshortened surfaces, and the well-known different effect between looking up or looking down a slope or hillside, invariably deceive all.

In thickets, or where the view is obstructed by old buildings, fences, etc, the manner of guessing out curves by the eye is of no value; it is but a home-made plan. "To have a character of art," says Mr. Loudon, " each separate curve ought to proceed, from its commencement to Its termination, in a uniform, uninterrupted degree of curvature".

All authors on landscape gardening are unanimous in their recommendations of curves of a strictly mathematical character. Downing especially makes some forcible suggestions in regard to them. Hogarth's line of grace and beauty was strictly geometrical; while Ruskin traces in the trees, clouds, undulations of surface, and in all natural objects an endless variety and combination of geometrical curves.

Ornamental road-building is an example of tasteful landscape engineering; the highest form of art, grace, and utility are dependent upon its skillful application; a finished polish and neatness characterizes its development, and it affords in all its combinations of beauty, utility, and economy, an absolute knowledge of the result. Scientific road-building is the true principle of economy; it shows the minimum amount of earth-work, the easiest and simplest manner of construction, and illustrates, in advance, the position, the grade, and the expense.

[One of our correspondents has expressed a purpose to criticise Mr. Woodward's remarks on geometrical curves. There can be no objection to this; let him therefore go ahead. He can have no difficulty in understanding Mr. Woodward's preferences, for they are decided, and pointedly expressed. - Ed].