We may observe with regard to the structure of these forts, that some of them have the habitable part of the building (which is always of a quadrangular form, and placed in the centre) surrounded by a double wall of very solid work; leaving a space between the walls, of ten, twenty, and thirty feet, sometimes of more, in which wells are occasionally found, and which may have served for the accommodation of the horses, sheep, or cattle of the garrison. Others have been built in one solid mass, with sloping sides, resembling the base of a pyramid, having only a square space left in the centre for the accommodation of the troops and the stowage of stores and provision. On these there is always a platform, and sometimes two, the sides of which form a glacis at a slope of from thirty to forty-five degrees, some of them being steeper than others: it seems probable that a parapet originally existed on the platforms of some of the forts, behind which the troops might more securely encounter their enemies; but on most of them there are now no traces of any defence of this nature, and the platform is left exposed. The lower platform is usually raised about ten and fifteen feet from the ground, and the upper one about eight or twelve feet above that. Trenches are rarely seen round the last mentioned buildings, but those enclosed within walls usually possessed that additional defence. Both are constructed with stone found in the neighbourhood, generally without any cement, particularly the sloping ones, although a very good cement may sometimes be observed in them: the most considerable forts are built with large and regularly-shaped stones, while the more unimportant are composed of stones of unequal forms and sizes, care being always taken, however, to leave a smooth surface on the slope of the glacis, in order to make the ascent more difficult. If we suppose that the greater number of these fortresses were built as defences against the attacks of the predatory natives, and not to resist the regular siege of a disciplined army, it may certainly be allowed that they were well calculated to afford security to their garrisons on such occasions; but their resources must soon have been exhausted by a continued blockade, the space enclosed being inadequate to contain many stores or much provision. As, however, there could scarcely have been any accommodation for horses or cattle in the pyramidal-shaped forts, which are by far the most numerous, more provision might certainly have been stowed in them than would at first sight be imagined. From the extreme height of the habitable part of these buildings in proportion to its breadth, we may conclude that it possessed an upper story, or, it may be, two; for otherwise a great portion of space would be thrown away: this fact, however, from their ruined state, could not be properly ascertained.