Introduced by Gerard Mercator, circa 1556: it is a projection of the surface of the earth in the plane, with all the meridians made parallel with each other, consequently the degrees of longitude all equal, the degrees of latitude increasing in a corresponding ratio towards the poles. This is the chart most commonly used in navigation; and its use appears to have obtained quickly, for in 1576, among the items of Martin Frobisher's outfit, we find, "For a greate Mappe Universall of Mercator, in prente, £1, 6 s. 8 d."