Egypt does not only lay claim to the oldest employment, and therefore probable invention, of the pointed arches, but also upon that of the circular arch.[26] Near the pyramids a group of tombs may be seen, the single blocks of which manifest the proper concentric way of cutting. They belong to the twenty-sixth Manethonic dynasty of the Psammetici, _i. e._ in the seventh and sixth centuries B.C., are therefore of about the same antiquity as the _Cloaca maxima_ and the _Carcer Mamertinus_ at Rome. We have also found tombs with vaults of Nile bricks, that go back as far as the era of the pyramids. Now I deny, in contradistinction to the opinion of others, that the brick arch, the single flat bricks of which are only placed concentrically by the aid of the trowel, admits of a previous knowledge of the actual principle of the arch, and particularly with respect to its sustaining power, of which denial there is already proof in the fact that before the Psammetici there is no instance of a concentrically laid arch, but many pseudo-arches, cut, as it were, in horizontal layers. But where the brick arch was ancient, we may also most naturally place the origin of the later concentric stone arch, or at least admit of its appearing contemporaneously in other lands. I was about to accompany the prince the next morning to the interesting institution of Herr Lieder, when Erbkam unexpectedly arrived from our camp. He reported that on the previous night, between three and four o’clock A.M., a number of shots were suddenly fired in the neighbourhood of our tents, and at the same time a crowd of more than twenty people rushed into the encampment. Our tents stand on a small surface before the rock tombs, which are excavated half-way up the steep wall of the Libyan Vale, and have a considerable terrace in front, formed by the rubbish. Almost the only way in which it was to be approached was on one side by a gorge that passes down from above by our tents. Thence the attack was made. It was first directed against the tent which served as a _salōn_ for our whole society. This soon fell down in a mass. Then followed the other great tent in which slept Erbkam, Frey, Ernst Weidenbach, and Franke. This was also torn down, and covered up its inhabitants, who had great difficulty in creeping out from among the ropes and tent-cloths. Besides this, all the guns had been placed in one tent together on the previous day, at the visit of the prince, and fastened to the centre pole, so that they were not at hand. The guards, cowardly in the extreme, and knowing that they had made themselves liable to punishment, even if such a thing had happened without their being in fault, immediately fled with loud cries in every direction, and have not yet returned. The thieves now stuck to what was nearest at hand, rolled everything they could lay hold of down the hill, and were soon lost in the plains below. Their shots had evidently been blank, for