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.