The voyage of William Ambrosia Cowley, master mariner, as recorded in manuscript Pepys 2826, commenced in August 1683 “from ye Capes Virginia to the isles of Cape Verde”, and from there to Guinea and so to 60°20′ S latitude”, south of the Falklands.
On the way Cowley had decided to use the Strait of Magellan to avoid the Horn and for this reason he diverted to bear WSW. By chance at about 47°S, several hundred miles north of the Falklands, at about the beginning of January 1684, he discovered the island which he named “Pepys”. The manuscripts Lambeth 642 and Morgan 3310 provide confirmation that the newly discovered island was ‘not laid down in the Drafts of the World’ (Lambeth) nor ‘before known or ever laid down in any map or draft (Morgan)’.
Furthermore, as Cowley reveals, “We saw likewise another island by this”, and this new island “appeared” on the second afternoon. Cowley had discovered two islands of a group, “and these islands that we saw I supposed to be the Sebaldes by the latitude and longitude” (i.e. the outer Falklands at 51°S.) How a mariner of his vast experience could have disbelieved his latitude fix and thought he must be four degrees farther south is difficult to imagine.
Aboard his ship was somebody else who also thought they were four degrees latitude more southerly than common sense dictated. This person was the explorer and ex-pirate William Dampier who stated (Dampier’s MSS Journal No.3236, Sloane Collection, British Museum): “January 28th 1684. We made the Sebald de Weerts. They are three rocky, barren islands without any tree, only some bushes. The two northernmost lie in 51°S, the other in 51°20’S. We could not come near the second northern island but we came close by the southern one.” According to Dampier, the privateer “Bachelor’s Delight”, master William Cowley, sailed directly across the South Atlantic from Guinea to the Sebaldes. The ship he was on, Cowley’s brig, made no detour to 47°S. The evidence of Dampier is that no island was ever discovered. And so why did Dampier and Crowley both lie?
Pepys Island discovered by Cowley was about 20 miles long, densely wooded throughout with much mountainous ground, ample fresh water and “a harbour which could take 500 ships.” This cannot possibly have been any of the three Sebaldes, nor can Pepys Island and the second island which materialized to join it have been the two “northernmost islands of the Sebaldes.” The mystery of Pepys Island was then put to rest in the Admiralty archives and it would be eighty years until interest in it revived for its possible use as a strategic naval base.