The geographical interest of my journey to Bardai did not consist solely in the discovery, to the east of the great chain traversed by Nachtigal, of mountains whose existence had not previously been suspected; it was greatly enhanced by the fact that my observations corrected serious errors of position and altitude committed by the famous German explorer on the itinerary he followed amid so many hardships. Thus, for example, in the site of Bardai there is an error of 50 miles in latitude and 30 in longitude; it is nearer 3000 than 2500 feet above sea-level; the height of the peaks of Toussidé and Timi is as much as 10,000 feet; the name of Tarso, which Nachtigal restricts to the massif he traversed, is a general term applied by the Tibestians to all mountainous regions consisting of high plateaux difficult of access, but on which the going is easy when once one has climbed to the top. Lastly, to the east of Bardai, instead of the great zone of plains shown on the maps there lies a succession of important massifs the culminating point of which rises as high as 8000 feet above the sea. Refusing, albeit with extreme reluctance, to listen to the urgent insistence of my amiable host Lieut. Blaizot, I left the post of Bardai on the evening of October 14, and by a moonlight march lasting almost all night I was able to get back on the 15th to my bivouac at Yountiou to make the observations, astronomical and other, requisite for checking those of the previous days; from that point I counted on returning to Miski, not by the already reconnoitred route passing through Yebbi, but by the Modra route lying further west, which was to afford me the opportunity of reconnoitring another passage. But a piece of news had just come which very much upset my Têda guide Mohammed: there had been fighting in the Modra valley between the Borkou troops and the hillmen, and he had very little fancy for guiding me through that region, where my detachment would presumably have to fight its way by main force. For me, on the contrary, it was a further reason for insisting on going there with all speed, in order to afford my companions, if need was, the help of the thirty rifles of my detachment. Mohammed allowed himself to be convinced by the promise of a suitable reward, and by the use of certain outer and visible signs indicating clearly that he did not guide me of his own free will: he adjusted a cord loosely round his neck, and one of my black soldiers seized hold of the other end. In the eyes of his own people his Têda honour was safe, and his responsibility for the consequences of the subsequent proceedings reduced to vanishing-point.