The only pointed arch actually discovered is of burnt brick.  The bricks are of the ordinary shape, and not intended for vaulting.  They are laid side by side up to a certain point, being bent into a slight arch by the interposition between them of thin wedges of mortar.  The two sides of the arch having been in this way carried up to a point where the lower extremities of the two innermost bricks nearly touched, while a considerable space remained between their upper extremities instead of a key-stone, or a key-brick fitting the aperture, ordinary bricks were placed in it longitudinally, and so the space was filled in.

[Illustration:  PLATE 59]

Another mode of constructing a pointed arch seems to be intended in a bas-relief, whereof a representation has been already given.  The masonry of the arcade in No.  V. [PLATE XLIX., Fig. 4] runs (it will be seen) in horizontal lines up to the very edge of the arch, thus suggesting a construction common in many of the early Greek arches, where the stones are so cut away that an arched opening is formed, though the real constructive principle of the arch has no place in such specimens.

With regard to the uses whereto the Assyrians applied the arch, it would certainly seem, from the evidence which we possess, that they neither employed it as a great decorative feature, nor yet as a main principle of construction.  So far as appears, their chief use of it was for doorways and gateways.  Not only are the town gates of Khorsabad found to have been arched over, but in the representations of edifices, whether native or foreign, upon the bas-reliefs, the arch for doors is commoner than the square top.  It is most probable that the great palace gateways were thus covered in, while it is certain that some of the interior doorways in palaces had rounded tops.  Besides this use of the arch for doors and gates, the Assyrians are known to have employed it for drains, aqueducts, and narrow chambers or galleries. [PLATE LVIII.  Fig. 2.]; [PLATE LIX., Fig. 1.]

It has been suggested that the Assyrians applied the two kinds of arches to different purposes, “thereby showing more science and discrimination than we do in our architectural works;” that “they used the pointed arch for underground work, where they feared great superincumbent pressure on the apex, and the round arch above ground, where that was not to be dreaded.” [PLATE LIX., Fig. 2.] But this ingenious theory is scarcely borne out by the facts.  The round arch is employed underground in two instances at Nimrud, besides occurring in the basement story of the great tower, where the superincumbent weight must have been enormous.  And the pointed arch is used above ground for the aqueduct and hanging garden in the bas-relief (see [PLATE XLIX., Fig. 4]), where the pressure, though considerable, would not have been very extraordinary.  It would seem, therefore, to be doubtful whether the Assyrians were really guided by any constructive principle in their preference of one form of the arch over the other.