(22) (2) By completely undercutting the obelisk. In spite of the slowness of the work I am convinced that the obelisk was completely undercut, most likely by hand pounding, since the expenditure of copper chisels would be terrific, and the idea, in this kind of work, seems to be to economise as much as possible on copper. It would be packed by wooden blocks or stone as near the centre as is consistent with stability, and in as few places as possible. Ropes would then be passed round the obelisk, each going several times round and being brought forward from below to anchorages in front. It is here that the details of this method assume such great importance; it must be remembered that, if the obelisk weighs 1170 tons (allowing a margin for the roughness of the undercutting below), and lies on its side on a hard bed, then the horizontal pull by ropes necessary to turn it over on to a new face will be half the weight of the obelisk, _i. e._ 585 tons. This would need 13,000 men, if a man pulls 100 pounds. I do not see how such a number could possibly be put on to this work. Figure 6 shews the obelisk supported on its packing, the section here being at the centre of gravity, and the outer edge of the packing being 1 metre from the centre of the obelisk on each side. To pull it over by horizontal ropes would need 8000 men, which still seems more than is practicable. It is possible to reduce the number of men required to turn the obelisk over by means of levers working off the north wall of the north trench, which seems to have been deliberately left for that purpose (cf. section 5). [Illustration: Fig. 6.] (23) By using, say, 30 21‐foot levers with a mechanical advantage of six to one, as described in the last section, the obelisk can be made to turn slightly about N (see fig. 6) so that the packing P can be removed and perhaps replaced by sand. About N the moment of the force at the bottom of the lever is to that of the weight of the obelisk acting at its centre as 7 : 2 (by scaling off the figure), so that the moment at the top of the lever to that of the weight will be 42 : 2, or 21 : 1. Let the number of men per lever be _n_. {25} Then 30 × 21 × 100 × _n_ = 1170 × 2240, which gives the number of men as 42, or 1260 men in all[9]. I have taken the amount of undercutting in figure 2 as .75 m. at the centre of gravity; it would increase as far as 1.00 metre at the butt. As soon as the sand had replaced the packing, the rock A⁠B would be removed by burning and wedging until it sloped down as much as possible from the level of the bed of the obelisk. I had not sufficient funds at my disposal to examine the levels of the rock to the centre of the valley, so I have to be rather vague as to what distance the obelisk was rolled out[10]. The obelisk would then, when the sand flowed out or was removed, take up a position as shewn in the dotted section.