(8) It would not be out of place, perhaps, to speculate for a moment on the method of obtaining a flat surface along the upper face of the obelisk. I think the method used was by means of boning rods—the method used to-day. For the benefit of those not acquainted with their use, a brief description will suffice. Boning rods are a set of equal, usually T-shaped pieces of wood. One is held upright at each end of the surface which it required to straighten. A man standing at either end, if he sight along the top of these boning rods, can see if a third boning rod, placed anywhere between them, is above or below the line joining them. Thus the surface can be tested anywhere along the obelisk until it is made to slope evenly down along its whole length. Boning rods for dressing moderately large blocks of stone are shewn in PETRIE, _Tools and Weapons_, plate XLIX, B 44–46. These measure only about 3 inches high and their tops were connected by a cord. In the case of an obelisk, the cord would be useless owing to the sag, so it seems probable that the sighting method described above was that employed by the ancient Egyptians. In the setting out of the obelisk, no allowance is made for the slight convexity or entasis, in a longitudinal and transverse sense, which is to be observed in most of the known obelisks. If there was to be a convexity, it was made at a later stage[4]. {8} [4] It will be noticed in plate I, nos. 2 and 3, that the slight convexity across the obelisk seen in some places, does not extend the whole length, neither is it even as regards either edge. (9) When the face of the obelisk had been made fairly flat by hammer-dressing, lines were scratched on it with a chisel, and filled in with black paint. The remains of the lines for the original scheme are clearly traceable. These are shewn on plate I, α and β. How much reduction was allowed for as regards the final dressing and polishing, we do not know; it was probably only the matter of a couple of centimetres. At the west end of the south trench the reduction of the side of the obelisk to the guide line has been begun. This can be seen at J to K on plate I. It now forms a kind of bevel and, as far as it extends, obliterates the vertical markings on the wall of the trench. On the east end of the north trench the trench itself has been moved inwards, from G to H, to be nearer the guide-line. The reason may either be that the workers found themselves too far from the guide-line, or that the guide-line was changed during the progress of the work, perhaps through fear of a fissure.