The form and position of the Central Park are peculiar in respect to this difficulty, and such that precedent in dealing with it is rather to be sought in the long and narrow Boulevards of some of the old Continental cities of Europe, than in the broad parks with which, from its area in acres, we are most naturally led to compare it. The Boulevards referred to are, however, generally used only as walks, not as drives or places of ceremony. In frequent instances, in order not to interrupt their alleys, the streets crossing them are made in the form of causeways and carried over on high arches. This, of course, destroys all landscape effect, since it puts an abrupt limit to the view. Some expedient is needed for the Central Park by which the convenience of the arrangement may be retained, while the objection is as far as possible avoided. [Sidenote: The present design.] In the plan herewith offered to the Commission, each of the transverse roads is intended to be sunk so far below the general surface that the park drives may, at every necessary point of intersection, be carried entirely over it, without any obvious elevation or divergence from their most attractive routes. The banks on each side will be walled up to the height of about seven feet, thus forming the protective barrier required by police considerations, and a little judicious planting on the tops or slopes of the banks above these walls will, in most cases, entirely conceal both the roads and the vehicles moving in them, from the view of those walking or driving in the park.[1] [1] NOTE, 1868.—In execution, the four traffic roads have been carried through the Park in the manner suggested. If the position which has just been taken with regard to the necessity for permanently open transverse thoroughfares is found to be correct, it follows necessarily that the 700 acres allowed to the new park must, in the first instance, be subdivided definitely, although it is to be hoped to some extent invisibly, into five separate and distinct sections, only connected here and there by roads crossing them; and if the plan of making these thoroughfares by sunken roads is approved, they will, as it appears to us, from the nature of the ground, have to be laid down somewhat on the lines indicated on the plan. If so, the problem to be solved is narrowed in its dimensions, and the efforts of the designer can be no longer directed to an arrangement that shall agreeably use up the space of 700 acres allotted, but to making some plan that shall have unity of effect as a whole, and yet avoid collision in its detailed features with the intersecting lines thus suggested. It is on this basis that the present plan has, in the first instance, been founded. If the sunken transverse roads were omitted, the design would not be less complete in character; but it is, on the other hand, so laid out that the transverse thoroughfares do not interfere materially with its general or detailed effect.