Our attention, commonly fixed on the vegetation of the country, was on this day chiefly engaged by the great range of mountains, no longer very distant, that bounded the horizon to the south. We had expected to find no difficulty in singling out the peak of Miltsin, described by Washington in the first volume of the Journal of the Royal Geographical Society, as the highest peak of the Atlas visible from the city of Marocco, and the altitude of which, as determined by a rough trigonometrical measurement, he fixes at 11,400 English feet. Approaching the city by a very different route from that of Washington, we soon convinced ourselves that there is no summit visible in the main range much surpassing its rivals in height, and we subsequently came to the conclusion, that Miltsin, which appears somewhat higher than its neighbours in the view from the city, is situated somewhat on the north side of the watershed, and therefore nearer to the observer than any other lofty summit of the range. It may fairly be inferred from Washington’s account that he had no opportunity for measuring a base-line—such as could allow him to determine accurately the height of distant summits. The conclusion to which we now came, and which was confirmed by our subsequent observations, was that the part of the main range within sight of Marocco and its neighbourhood is remarkably uniform in height. There are many prominent points that probably approach the limit of 13,500 English feet, and no depressions that fall more than about 2,000 feet below that height, This, as will be seen hereafter, does not apply to the westerly part of the chain lying west of the sources of the Oued Nyfs, but this is only imperfectly seen from the neighbourhood of Marocco. The day was hotter than any we had yet experienced, the temperature in the shade being about 85° Fahr., and the breeze which usually rises during the hottest hours was scarcely felt. But the vicinity of lofty mountains usually determines strong currents in the heated air, and these must have been at work, though unfelt by us. As we looked towards the mountain chain, we noticed lofty columns of sand or dust, remarkably uniform in shape, that travelled steadily westward across the plain in the opposite direction to the breeze, so far as this could be detected. At one time as many as three of these were seen at the same time, each moving independently. These miniature cyclones, arising from the interference of opposite currents of air, are not uncommon in the plains on the south side of the Alps, but are rarely to be seen on so great a scale as here.