The cause of this deviation lay probably in the fact that, on this side, a low rocky spur ran out from the mountain-range in this direction, and that it was thought desirable to accommodate the line of the structure to the natural irregularities of the ground.

In addition to the irregularity of general outline thus produced, there is another of such perpetual occurrence that it must be regarded as an essential element of the original design, and therefore probably as approving itself to the artistic notions of the builder.

This is the occurrence of frequent angular projections and indentations, which we remark on all three sides of the platform equally, and which would therefore seem to have been regarded in Persia, no less than in Assyria, as ornamental.
[Illustration: PLATE XL.] The whole of the platform is not of a uniform height.

On the contrary, it seems to have been composed, as originally built, of several quite distinct terraces.

Three of these still remain, exhibiting towards the west a very marked difference of elevation.