It is also probable what is delivered concerning the variation of the Compass that is the cause and ground thereof, for the manner as being confirmed by observation we shall not at all dispute. The variation of the Compass is an Arch of the Horizon intercepted between the true and Magnetical Meridian; or more plainly, a deflexion and siding East and West from the true Meridian. The true Meridian is a major Circle passing through the Poles of the World, and the Zenith or Vertex of any place, exactly dividing the East from the West. Now on this line the Needle exactly lieth not, but diverts and varieth its point, that is, the North point on this side the Equator, the South on the other; sometimes on the East, sometime toward the West, and in some few places varieth not at all. First, therefore it is observed that betwixt the Shore of _Ireland_, _France_, _Spain_, _Guiny_, and the _Azores_, the North point varieth toward the East, and that in some variety; at _London_ it varieth eleven degrees, at _Antwerp_ nine, at _Rome_ but five: at some parts of the _Azores_ it deflecteth not, but lieth in the true Meridian; on the other side of the _Azores_, and this side of the Equator, the North point of the Needle wheeleth to the West; so that in the latitude of 36 near the shore, the variation is about eleven degrees; but on the other side the Equator, it is quite otherwise: for about _Capio Frio_ in _Brasilia_, the South point varieth twelve degrees unto the West, and about the mouth of the Straits of _Magellan_ five or six; but elongating from the coast of _Brasilia_ toward the shore of _Africa_ it varieth Eastward, and arriving at _Capo de las Agullas_, it resteth in the Meridian, and looketh neither way. [Sidenote: _The cause of the variation of the Compass._]