Map of Greenland and Iceland, 1770.
Passages from east to west Greenland are charted. The Ferro Meridian which was used in the history as a Prime Meridian crosses Iceland. It was established based on the longitude of the island of El Hierro, the westernmost island of the Canary Islands. Already since the era of Ptolemy (2nd century A.D.) the Canary Islands were considered the westernmost land of the known World. The Greenwich Prime Meridian was established by English astronomer and mathematician Sir George Biddell Airy in 1851. The Prime Meridian used today is the International Reference Meridian which passes approx 102m of the Greenwich Royal Observatory.
“Authobiography of Sir George Biddell Airy” includes birth story of the Greenwich Prime Meridian.