The Sorata and Illimani were first measured by a distinguished geologist, Mr. Pentland, in 1827, and also in 1838. Since the publication, in June 1848, of his great map of the basin of the lake of Titicaca, we know that the above-mentioned elevations of these two mountains are respectively 3960 and 2851 English feet, too great. The map gives to the Sorata 21286, and to the Illimani 21149 English feet. A more exact calculation of the trigonometrical operations of 1838 has led Mr. Pentland to these new results. There are, according to him, in the western Cordillera four peaks of from 21700 to 22350 English feet. The highest of these, the peak of Sahama, would thus be 926 English feet higher than the Chimborazo, and but 850 English feet lower than the Volcano of Acongagua, measured by the expedition of the Beagle (Fitz Roy’s Narrative, Vol. ii. p. 481.) [6] p. 3.--“_The Desert near the basaltic mountains of Harudsh._” Near the Egyptian Natron Lakes, (which in the time of Strabo had not yet been divided into six reservoirs), there is a range of hills which rises steeply on the northern side, and runs from east to west past Fezzan, where it finally appears to join the chain of the Atlas. It divides in north-eastern Africa, as the Atlas does in north-western Africa, the inhabited maritime Lybia of Herodotus from the land of the Berbers, or Biledulgerid, abounding in wild animals. From the limits of Middle Egypt the whole region south of the 30th degree of North latitude is a sea of sand, in which are dispersed islands, or Oases, containing springs of water and a flourishing vegetation. The number of these Oases, of which the ancients only reckoned three, and which Strabo compared to the spots on a panther’s skin, has been considerably augmented by the discoveries of modern travellers. The third Oasis of the ancients, now called Siwah, was the Nomos of Ammon; a residence of priests, a resting place for caravans, and the site of the temple of the horned Ammon and the supposed periodically cool fountain of the Sun. The ruins of Ummibida, (Omm-Beydah), belong incontestibly to the fortified caravanserai at the temple of Ammon, and therefore to the most ancient monuments which have come down to us from the early dawn of civilization. (Caillaud, Voyage à Syouah, p. 14; Ideler in den Fundgruben des Orients, Bd. iv. S. 399-411). The word Oasis is Egyptian, and synonymous with Auasis and Hyasis (Strabo, lib. ii. p. 130, lib. xvii. p. 813, Cas.; Herod. lib. iii. cap. 26, p. 207, Wessel). Abulfeda calls the Oases, el-Wah. In the later times of the Cæsars, malefactors were sent to the Oases; being banished to these islands in the sea of sand, as the Spaniards and the English have sent criminals to the Falklands or to New Holland. Escape by the ocean is almost easier than through the desert. The fertility of the Oases is subject to diminution by the invasion of sand.