There are over seventy gateways or interruptions in the embankment, at irregular intervals along its line. For reasons heretofore given, it is difficult to believe they were all designed as places of ingress or egress. We can only account for their number, upon the hypothesis that they are places once occupied by block-houses or bastions composed of timber, and which have long since decayed. These openings appear to have been originally about ten or fifteen feet in width.
This work, it will be seen, consists of two grand divisions, the passage between which is long and narrow. Across this neck is carried a wall of the ordinary dimensions, as if to prevent the further progress of an enemy, in the event of either of the principal divisions being carried,—a feature which, while it goes to establish the military origin of the work, at the same time evinces the skill and foresight of the builders. This foresight is further shown, in so managing the excavations necessary for the erection of the walls, as to form numerous large reservoirs; sufficient, in [p021] connection with the springs originating within the work, to supply with water any population which might here make a final stand before an invader. Even in the absence of these sources, surrounded as the work is on every hand by streams, it would be easy, in face of the most formidable investment, to procure an adequate supply.
At numerous points in the line of embankment, and where from position they would yield the most effective support, are found large quantities of stones. These are water-worn, and seem, for the most part, to have been taken from the river. If so, an incredible amount of labor has been expended in transporting them to the places which they now occupy,—especially will it appear incredible, when we reflect that all of them were doubtless transported by human hands.
A review of this magnificent monument cannot fail to impress us with admiration of the skill which selected, and the industry which secured this position. Under a military system, such as we feel warranted in ascribing to the people by whom this work was constructed, it must have been impregnable. In every point of view, it is certainly one of the most interesting remains of antiquity which the continent affords.