Note 378 — Chapter I · (continued 2)

There was a tendency in the latter part of the sixteenth century to remove the prime meridian to St. Michael’s, in the Azores, for the reason that there was no variation in the needle there at that time, and in ignorance of the forces which to-day at St. Michael’s make it point twenty-five degrees off the true north. As late as 1634 a congress of European mathematicians confirmed it at the west edge of the Isle de Fer (Ferro), the most westerly of the Canaries.