When I had completed the original computing and plotting, I sent the results to Dale Dunlap of Annapolis, Maryland, for vetting. Mr. Dunlap, a navigation authority, was co-author of the navigation text used by midshipmen at the U. S. Naval Academy. In general he confirmed the results, but in the course of research he discovered an electrifying piece of information that sent me back to the computers.
In his collection of old texts on navigation, Mr. Dunlap has a copy of a book originally published in 1594. It is by Master Thomas Blundeville, who states: “you have to note that every Spanish league containeth 2857 fathams’ and that our English league containeth no more but 2500 fathams . . . and every fatham containeth 6 foote.” There in plain Elizabethan English is the answer to that vexed question, how long was an Iberian sea league? A little arithmetic gives the answer: 2.82 nautical miles.
Mr. Dunlap’s discovery moved me to search through my own navigation library. I found the same definition in William Bourne’s A Regiment for the Sea, an English navigation manual published in 1574, 20 years earlier than Blundeville, only 68 years after the death of Columbus. Bourne gives the same figure for the Portuguese league. He says: “Whereby you may know iustly how many leagues and parts of a league the ship goeth in an houre. For an English league cloth contained .2500. Far-dome. And a Spanish or porting ale league doth contain 2857 fandom’s.”
Thus we have on record, in practical sailor’s manuals of the period, the actual length of the Iberian sea league, and have no need to rely on conjecture. The recomputed course, using a league of 2.82 nautical miles and incorporating current and leeway, because of the push of the current again came out too far west. Measuring the overrun back to the first possible landfall, I found an excess of 9 percent. Recalculating the daily distances less this percentage, we come to a position some ten miles east-northeast of Samana Cay.
Marc Auslander, a research scientist with IBM, recomputed my figures using a more powerful computer, into which he had entered the total winds of all the wind roses along the transatlantic track, giving an even closer evaluation of possible leeway, and took my figures to more decimal places. This fine-tuning gave us a final fix of 23° 09′ 00″ N latitude and 73° 29′ 13″ W longitude.
We cannot say that we have established with absolute certainty the precise point of Columbus’s landfall. Currents may vary, and there are still unknown factors. But unless some new data (such as the finding of the original Columbus log in his own hand) were to emerge, we can say, in the present-day navigator’s parlance, that latitude 23° 09′ 00″ N and longitude 73° 29′ 13″ W is “the most probable position” of Christopher Columbus’s first landfall in the New World.
It remains now for a sailing vessel to take a departure from the barcelona accommodation in September and to steer Columbus’s courses by compass alone, due west where he went due west and elsewhere where he deviated, and see where it ends up. In Spain timber has already been cut and is seasoning to build replicas of Santa Maria, Nina, and Pinta. In 1992, on the quincentennial of the discovery, they will set sail for the New World. Let them steer by compass and the Admiral’s log alone, and they too may unfurl the green-crossed banner of the Most Catholic Monarchs on the soil of Columbus’s true San Salvador.