It is generally supposed that the slave trade originated in the fact that in certain parts of Central Africa there are no horses or beasts of burden, as owing to the existence of the tetse-fly no animal can live. Consequently ivory and everything else has to be carried on the heads of porters. These porters were engaged by the Arab ivory dealers in the interior, and marched in large gangs to the seaports. Having reached their destination, and given up their loads, the question of transport back to their villages would arise. The Arab traders found that it would suit their purpose best to sell the porters as slaves. Who was to know whether or not they were taken in battle? In Mohammedan countries, so long as plenty of backsheesh is forthcoming, those in authority ask few questions. Soon the sale of slaves became more profitable than the ivory trade, which possibly had originated it, and so the one was substituted for the other, the authorities not only winking at it, but encouraging it as a source of large revenues to them. At one time a large number of so-called Christians were engaged in this unholy traffic, but the scandal became so great that European public opinion would not tolerate it, and so they had to sell their stations to Mohammedan Arabs, who if possible were even more cruel and relentless in the way they conducted the trade. Merchant princes arose among them, and they carried on their business with a thoroughness and a system worthy of a better cause. Soldiers were trained, and large armies kept for no other purpose than that of collecting slaves. Peaceful villages were surrounded, night attacks were made, whole tribes were marched off to the slave markets, the road being lined by grinning skulls to show the way in which the victims suffered _en route_. "Not for this Was common clay ta'en from the common earth, Moulded by God, and tempered with the tears Of angels, to the perfect shape of man!" The unfortunate captives were chained together to prevent escape, and often the fastenings were secured in a way so unnecessarily cruel, that they had great difficulty in securing any sleep, either at night or during the day when the periodical halts were made. Indeed the ordinary precautions that we take in the convoy of large herds of cattle were generally neglected. This is all the more surprising when we consider what great trouble these men took to secure their victims; one would have thought that self-interest at least would often have dictated a more humane policy, but it does not appear to have been so. * * *