The oldest possession in this region and the southernmost of the three great provinces of this important British territory is the Gold Coast Colony proper, which lies between Ashanti and the sea and covers an area of 24,200 square miles. Celebrated for its alluvial gold from prehistoric times onwards, it has of late become more remarkable for its rock gold from reefs of quartz and auriferous conglomerates. To work these more efficiently a railway was constructed from Sekondi to the interior by 1908, with a branch line. The average value of the gold exported annually since 1907 is about one million sterling. Since the beginning of the 20th century there has been a great development of cacao planting amongst the natives, on their own land; and the importance of this movement and its profitable results has quite changed the European conception of African colonization. It is now realized that the native proprietor works far harder on his own land if there is a market for his produce than he does as a paid servant on a European-owned estate. Although the Gold Coast is perhaps the most unhealthy of the British West African possessions, it is prosperous in its finances, and has made great progress in trade. In the last ten years the total value of its trade has quadrupled, and stands now at £6,000,000 in approximate yearly value. The colony of Lagos came into existence in 1863[116]. It was afterwards added to the government of the West African Settlements, then attached to the Gold Coast; and finally in 1886 made an independent colony. Lagos, as its name shows, was originally a discovery of the Portuguese, who so named it from the large lagoon, which until recently was a harbour of very doubtful value, even on this harbourless coast, but is now by a vast expenditure of money rendered safe for the exit and entrance of steamers at high tide. In the days of the early Portuguese adventurers the modern territory of Lagos was partly under the influence of Dahomé, partly under the rule of Benin; and the Portuguese and subsequently the British came there to buy slaves which native warfare rendered so abundant. In prosecuting the crusade against the slave trade in the middle of the last century the British Government came into contact with the king of Lagos, who had become one of the most truculent slave traders on the coast. This king, Kosoko, was expelled by a British naval expedition in 1851, and his cousin was placed on the throne, after having made a treaty with the British binding himself to put down the slave trade. A British consul was appointed to superintend the execution of this treaty, but neither the king who signed it nor the son who succeeded him kept faithfully to its provisions. At length, in 1861, the king of Lagos ceded his state to the British Government