46 THE EXPLORATION OF THE NIGER averts a catastrophe by letting every one know how to avoid the obstacle. A great galloping now ensues to catch up the leading cart, and this time the difficult place is passed without accident ; but often enough a wheel slips into the bc, and in spite of all the poor mule's tugging at her collar there it sticks. We all have to rush to the rescue, drivers and coolies literally put their shoulders to the wheel, and with shouts of encouragement and oaths they finally extricate it. It is out again at last, and we resume our march.

Then we come perhaps to what is called a marigot in West Africa, that is to say, a little stream which is dried up part of the year, and is a characteristic feature of the country. Before the rainy season it has probably been bridged roughly over, and a few planks have been thrown down at its edge, but in the torrential downpours of rain of the winter the planks have sunk, and the bridge has