The business of ostrich farming is in the hands of several large companies, and, next to the wool-crop, ostrich plumes are the leading product. There are about a quarter of a million birds, and each produces about one pound of feathers. The ordinary quality of plumes varies from five to ten dollars a pound; very choice plumes command as much as two hundred dollars a pound. London is the chief market for them, but most of them sooner or later find their way to the milliners of the great cities. The diamond-mines of Griqualand West furnish practically the whole of the world's supply. The mines are operated on a most thorough business system, and the output of rough stones is carefully regulated to meet the demand. All wholesale dealers know the output from year to year, and no more stones are put upon the market than the number required to meet the demand. All the Kimberley mines are now consolidated under one company. The yearly output does not vary much from twenty million dollars' worth of stones. The stones are marketed from Kimberley, but London dealers buy most of them. The mines that for several years produced more gold than any others in existence are in the Transvaal.[82] Other undeveloped mines in the territory of Rhodesia are known to be extremely rich in precious metals; indeed, there is much evidence that the famous mines of Ophir were in this region. Copper ore is an important export. The industries of Natal colony do not differ materially from those of Cape of Good Hope. The rainfall is sufficient for the growing of sugar-cane, and sugar is an important export to the mother-country. The colony has productive coal-mines, and these are destined to become an important resource. The home government has encouraged railway building, and a trunk line through Rhodesia affords an outlet to the ports of the south coast. It is the policy of the mother-country to extend this road along the lake-region and the Nile Valley (known as the "Great Rift") to the Mediterranean Sea. This plan when carried out will give Great Britain a practical control of the trade of eastern Africa. The imports are mainly textiles, machinery, and steel wares. _Cape Town_ is the most important centre of trade in South Africa. A considerable trade, however, is carried on at _Port Elizabeth_ and at _Durban_, the port of Natal. _Kimberley_ is the seat of the diamond-mining interests, and _Johannesberg_ of the gold-mines. Germany and Portugal divide the southwest coast. _Walfisch Bay_ is the outlet of the former. Portuguese East Africa is an outlet for the trade of the Transvaal region, with which it is connected by rail. The port _Lourenco Marquez_ has a fine harbor. QUESTIONS FOR DISCUSSION Has the partition of Africa been an advantage or a disadvantage to the native races of the continent? What advantages will accrue to Great Britain from the Cape to Cairo railway?