25. In Mauch Ruins in divisional wall.
26. In Mauch Ruins in east main wall.
27. In Mauch Ruins in east wall of the outer enclosure.
THE BATTERING OF WALLS
The backward incline of both faces of walls from their bases to summits is a general characteristic in ancient architecture at Zimbabwe, and in all other ruins which belong to the earliest known type of ancient buildings in this country. This feature, so far as examinations have been made, is conspicuous by its absence from all buildings of the second or later period. So noticeable is this feature in the main walls of the Elliptical Temple that visitors viewing the walls from the interior constantly affirm their belief that the walls have commenced to lean over towards the exterior, and when viewing the exterior faces of the identical walls declare that the walls are leaning inwards and must ultimately fall inside the building. This is a mere optical delusion.
The main walls, portions of which are believed to have stood some 3,500 years, are, if given the same conditions to which they have been subjected in past times, quite likely to be standing at the end of another millennium, if not longer, for the battering-back is a most important element of their massive strength, and has proved to be the main factor in securing their durability. Of course, some main walls in certain places show signs of bulging out and of damage caused by earth movements, possibly earthquakes, also by lightning, the sinking of foundations by water or damp, or growth of trees within their open dry masonry during the long period since their erection. Some faces of the walls show a complete swagging from end to end of their lengths, and yet the batter-back has preserved the walls practically intact throughout with each block occupying its original relative position. The appearance of such walls strongly suggests the effects of earthquake, and while these earth-movements would destroy a plumb wall, a wall with a severe batter-back, such as is seen in all the older walls at Zimbabwe, would on this account be comparatively safe from such effects.
In some instances the battering is very severe and exceeds that of 1 ft. in 6 ft., and the native labourers can scale such with ease. Looking at the rounded extremities of any of the most ancient walls, one notices that their sides resemble the lines of a lighthouse as popularly conceived, in many instances the batter-back being more severe near the base and near the summit, and many of such rounded ends of walls where still perfect show very graceful lines of battering. So carefully is the batter-back worked out in the courses that looking up or down the face of the wall one can scarcely see a quarter of an inch of face of protruding block out of the line of the battering.
To secure the batter of the walls the blocks are not slanted downwards at their inner side, but are laid on a true dead level reaching from face to face of the wall on either side, and in their outer courses their outside edges are placed back from the outer course below. So slightly do these courses recede one above another that in the height of only a few courses it would be almost impossible to detect the presence of any battering, while it is very decidedly noticeable in a height of some few feet.
Bent’s estimate of the extent of the battering of walls at Zimbabwe, namely, 1 ft. in 6 ft., is fairly exact with regard to many of the walls, but excessive with regard to others, such as the main walls of the Elliptical Temple, while for many walls it is perfectly correct. The battering in most instances being more perceptible near base and summit than on the intermediate face of the wall, and the summits in many cases having disappeared, the batter-back, as ascertained by plumb lines, has consequently been considerably reduced. Where the original summits are still practically intact, and where there have been no bulging out of the faces of the walls, and the top courses on the edges do not lean outwards as they frequently do, on account of creeper and tree growths, the 1 ft. in 6 ft. is frequently approached, for instance, south wall Western Temple, 4 ft. 8 in. in 31 ft.; Pattern Passage, 2 ft. in 13 ft. In low walls 1 ft. in 6 ft. is very frequently reached.
The main walls of the Elliptical Temple, as shown in the Table of Battering (see Elliptical Temple, Main Wall, Chapter IX.), are much less than 1 ft. in 6 ft., a fair average for inside faces being 1 ft. in 11 ft., but at some points it is only 1 ft. in 15 ft., and for outside faces 1 ft. in 10 ft. and 1 ft. in 8 ft.