It is difficult to describe the limit of an elephant's swimming powers; this must depend upon many circumstances, whether it is following the stream or otherwise, but the animal can remain afloat for several hours without undue fatigue. The displacement of an elephant's carcase is less than the weight of water, although it swims so deeply immersed that it would appear to float with difficulty. An elephant shot dead within the water will float immediately, with a considerable portion of one flank raised so high above the surface that several men could be supported, as though upon a raft. The body of a hippopotamus will sink like a stone, and will not reappear upon the surface for about two hours, until the gas has to a certain degree distended the carcase: thus the hippopotamus is of a denser and heavier material than the elephant, although it is an aquatic animal. When tame elephants cross a river they are conducted by their drivers, who stand upon their backs, either balancing themselves without assistance, or supported by holding a cord attached to the animal's neck. It is very interesting to watch the passage of a large river by a herd of these creatures, who to a stranger's eye would appear to be in danger of drowning, although in reality they are merely gamboling in the element which is their delight. I have seen them cross the Brahmaputra when the channel was about a mile in width. Forty elephants scrambled down the precipitous bank of alluvial deposit and river sand: this, although about thirty-five feet high, crumbled at once beneath the fore-foot of the leading elephant, and many tons detached from the surface quickly formed a steep incline. Squatting upon its hind-quarters, and tucking its hinder knees beneath its belly, while it supported its head upon its trunk and outstretched fore legs, it slid and scrambled to the bottom, accompanied by an avalanche of earth and dust, thus forming a good track for the following herd.