In 1427, again, with the co-operation of his father King John, he seems to have sent out the royal pilot Diogo de Sevill, followed in 1431 by Goncalo Velho Cabral, to explore the Azores, first mentioned and depicted in a Spanish treatise of 1345 (the Conosrimiento de todos los Reynos) and in an Italian map of 1351 (the Laurentian Portolano, also the first cartographical work to give us the Madeiras with modern names), but probably almost unvisited from that time to the advent of Sevill.
This expedition confirmed by cartographical evidence the non-existence of Peary Channel, a fact established by M.
The first sufficient explorations for cartographical record were made by John Smith in 1614, and his map was long the basis - particularly in its nomenclature - of later maps.
Of great value for cartographical work is a careful survey, carried out by American engineers (1897-1898), for a continental railway running along the west coast from Mexico to Chile.
Arrowsmith established himself in London in 1770 (General Atlas, 1817), but the cartographical business ceased on the death of John Arrowsmith in 1873.