28th Dec.--At work at break of day. Completed the repair of yard, which is disgracefully faulty. Re-rigged the mast. Poor Johann will die, I much fear. His constitution appears to be quite broken up; he has become deaf, and there is every symptom of decay. I have done all I can for him, but his voyage in this life is nearly over. Ship in order, and all sailed together at 2:15 p.m. Strong north wind. Two vessels from Khartoum passed us while repairing damages. I rearranged the donkeys, dividing them into stalls containing three each, as they were such donkeys that they crowded each other unnecessarily. Caught a curious fish (Tetrodon physa of Geof.), that distends itself with air like a bladder; colour black, and yellow stripes; lungs; apertures under the fins, which open and shut by their movement, their motion being a semi-revolution. This fish is a close link between fish and turtle; the head is precisely that of the latter, having no teeth, but cutting jaws of hard bone of immense power. Many minutes after the head had been severed from the body, the jaws nipped with fury anything that was inserted in the mouth, ripping through thin twigs and thick straw like a pair of shears. The skin of the belly is white, and is armed with prickles. The skin is wonderfully tough. I accordingly cut it into a long thong, and bound up the stock of a rifle that had been split from the recoil of heavy charges of powder. The flesh was strong of musk, and uneatable. There is nothing so good as fish skin--or that of the iguana, or of the crocodile--for lashing broken gun-stocks. Isinglass, when taken fresh from the fish and bound round a broken stock like a plaster, will become as strong as metal when dry. Country as usual-- flat and thorny bush. A heavy swell creates a curious effect in the undulations of the green rafts upon the water. Dinka country on east bank; Shillook on the west; course south; all Arab tribes are left behind, and we are now thoroughly among the negroes.