systematic exploration of the Atlantic, which constitutes their title to renown during the age of the great nautical expeditions. On this occasion they saw nothing but the reefs of Formigas between San-Miguel and Santa-Maria; but Gongalo Velho Cabral, returning to these waters next year, discovered Santa-Maria itself, which Don Henri presented to him as a fief. Twelve years afterwards he landed on San-Miguel, the chief island in the archipelago, which he also received in vassalage under the Portuguese crown. The eastern group of Cabrera, or Las Cabras, had already formed part of geographical nomenclature, but another twenty years passed before the last of the nine members of the group was finally surveyed.
Although scattered over a vast space, the islands have many features in common. All are hilly and dominated by volcanic craters whence lava streams have been discharged, and all terminate seawards in rugged masses of black scoria
presenting a forbidding aspect. With the exception of Santa-Maria, at the southeastern extremity, which contains some limestone beds dating from the Miocene period, all are composed exclusively of ashes, scoriæ, and lavas. Geographically they form three perfectly distinct groups, of which the easternmost is the largest, although comprising only the two islands of San-Miguel and Santa-Maria, with the reefs of Formigas, which may be regarded as the crests of a submerged rocky islet.
The central group consists of five members — Terceira, which has at times given its name to the whole archipelago; Graciosa, San-Jorge, Pico, and Fayal. The
