by William Gilbert

“ For on the meridian passing through Plymouth in Latitude 60 degrees the North-easterly variation is greater: in Latitude 40 deg. much less; in Latitude 20 deg. very small indeed. On the meridian of Corvo, although there is no variation near the island, yet in Latitude 55 degrees the variation is about 1⁄2 a rumbe to the North-west; in Latitude 20 deg. the versorium inclines 1⁄4 of a rumbe toward the East. ”

“ From hence the Northeasting [Anatolismus] beginneth to decrease, til you come to Helmshude (which place is Westward from the North Cape of Finmark) where againe the needle pointeth due North. Now the longitude from Coruo to Helmshude is 60 degr. ”