It was only after having landed in Britain that Cæsar was able to form a tolerably exact idea of its form and extent. “Britain,” he says, “has the form of a triangle, the base of which, about 500 miles in extent, faces Gaul. The side which faces Spain, that is, the west, presents a length of about 700 miles. In this direction the island is separated from Hibernia (_Ireland_) by an arm of the sea, the breadth of which is apparently the same as the arm of the sea which separates Britain from Gaul;” and he adds that “the surface of Hibernia represents about one half the surface of Britain. The third part of the triangle formed by this latter island is eastward turned to the north, and 800 miles long; it faces no land; only one of the angles of this side looks towards Germany.”[312] These imperfect estimates, which were to give place in the following century to others less inaccurate,[313] led the great captain to ascribe to the whole of Britain twenty times 100,000 paces in circuit. He further gathered some information still more vague on the small islands in the vicinity of Britain. “One of them,” he writes, “is called Mona (_the Isle of Man_), and is situated in the middle of the strait which separates Britain from Hibernia.” The Hebrides, the Shetland islands (_Acmodæ_ of the ancients), and the Orcades, which were only known to the Romans at the commencement of our era,[314] were confounded, in the minds of Cæsar and his contemporaries, with the archipelago of the Feroe isles and Scandinavia. Caledonia (_Scotland_) appeared only in an obscure distance. Cæsar represents the climate of Britain as less cold and more temperate than that of Gaul. With the exception of the beech (_fagus_) and the fir (_abies_), the same timbers were found in the forests of this island as on the neighbouring continent.[315] They grew wheat there, and bred numerous herds of cattle.[316] “The soil, if it is not favourable to the culture of the olive, the vine, and other products of warm climates,” writes Tacitus,[317] “produces in their place grain and fruits in abundance. Although they grow quickly, they are slow in ripening.” Britain contained a numerous population. The interior was inhabited by peoples who believed themselves to be _autochthones_, and the southern and eastern coasts by a race who had emigrated from Belgic Gaul, and crossed the Channel and the Northern Sea, attracted by the prospect of plunder. After having made war on the natives, they had established themselves in the island, and became agriculturalists.[318] Cæsar adds that nearly all these tribes which had come from the continent had preserved the names of the _civitates_ from whence they had issued. And, in fact, among the peoples of Britain named by geographers in the ages subsequent to the conquest of Gaul, we meet, on the banks of the Thames and the Severn, with the names of Belgæ and Atrebates.