C. Julius Caesar, Gallic War

The island is triangular in its form, and one of its sides is opposite to Gaul. One angle of this side, which is in Kent , whither almost all ships from Gaul are directed, [looks] to the east; the lower looks to the south. This side extends about 500 miles. Another side lies toward Spain and the west, on which part is Ireland , less, as is reckoned, than Britain, by one half: but the passage [from it] into Britain is of equal distance with that from Gaul. In the middle of this voyage, is an island, which is called Mona: many smaller islands besides are supposed to lie [there], of which islands some have written that at the time of the winter solstice it is night there for thirty consecutive days. We, in our inquiries about that matter, ascertained nothing, except that, by accurate measurements with water, we perceived the nights to be shorter there than on the continent. The length of this side, as their account states, is 700 miles. The third side is toward the north, to which portion of the island no land is opposite; but an angle of that side looks principally toward Germany . This side is considered to be 800 miles in length. Thus the whole island is [about] 2,000 miles in circumference.