FROM TIMBUKTU TO TOSAYE 99 blessing that his cowardice overcame the desire for doing evil. He might have proved a great source of danger, especially at Say, his native place, where he would have aided and abetted our enemies.

The first and most important object of the expedition was to trace as correctly as possible the course of the river which we had to follow. For this purpose I had observing instruments of very accurate construction made for each barge, which would afford us the means of making a triangulation of the river en route. Two barges were to coast along the banks, while the third kept in the deep channel.

We tried this plan on January 23, the first day on which we navigated an almost unknown region. It was soon found impracticable. By evening we had gone less than four and a half miles. At this rate, counting necessary stoppages, it would take a year to reach the mouth of the river. We therefore adopted the following plan : the Davoiist followed the left bank ; the Aube the right one while on surveying duty, the two barges frequently taking their places.

At the same time, Baudry on the Dantec tacked about in search of the deep channel, taking frequent soundings. Any inaccuracies were guarded against by taking the mean draught of the two larger vessels, and constantly determining the position by astronomical observations. This system was invariably followed down to Ansongo, that is, for the whole navigable course of the Niger. Though we did not secure the accuracy of a regular survey, still to me it appeared quite enough ; for the first vessels that might come after us, will possess an indication of the position of the deep channel relatively to the banks and their configuration, the distances from one point to another, the position of the villages, and the peculiarities of the soil, etc.