"Columbus Used Dead Reckoning Navigation in His 1492 Voyage of Discovery to the New World" by Douglas Peck in "Encounters: A Quincentenary Review" (Summer 1990, pp. 18-21) Some controversy has arisen among scholars concerning whether Columbus used dead reckoning navigation or latitude sailing navigation to make his landfall on Guanahani in the New World. The question begs an answer since the use of one method as opposed to the other could mean a north-south difference of several hundred miles in reconstructing his track across the Atlantic to his landfall island. To understand and solve the problem, we must first accurate- ly define the two navigation methods: Latitude Sailing: A method used by many of the early naviga- tors when their destination was known to be on a particular latitude and east or west of their position. The vessel would be sailed either north or south to the desired latitude, determined by sightings on Polaris (or the stars revolving around Polaris) or the sun, and then sailed along that latitude to the destina- tion. This method was used by early navigators prior to advent of the magnetic compass in the thirteenth century and thereafter used in conjunction with the compass to maintain the desired latitude. Dead Reckoning: The course is sailed on any desired compass heading and the position is determined by the distance covered on that heading from a known geographical point of land. This method required plotting the course on a chart to a certain scale to arrive at the latitude and longitude of the destination or to the relative position related to the departure point. Dead reckoning was the navigation method used by Columbus as revealed in a study of his log and his letters concerning his voyages. He constantly and meticulously recorded his every change of compass heading and the distance covered on that heading, which is a requirement for dead reckoning. Never once in the crossing did he refer to using the quadrant or eyeballing Polaris to determine his latitude. His sole reference to Polaris was when he calmed the fears of his crew who had noticed the unknown (and to them, frightening) westerly variation of the compass by explaining (quite correctly) that the pole star revolved several degrees around true north and so the apparent variation of the compass would be different at different times of the evening or early morning. As thoroughly researched and documented by both Taviani and Morison, Columbus was a product of the Genoese-Mediterranean and the Portuguese school of seafaring and navigation, which used exclusively dead reckoning for navigating to their destinations. Portuguese astrologers (as opposed to seafaring navigators) did give latitudes from some of their trading posts and islands by celestial observations on land, but there is no indication that these learned men had any part in the navigation of the vessels that sailed to and discovered these areas. In directing the Spanish captains of the vessels on the second, third, and fourth voyages, Columbus always gave a compass course and distance to the destination, never once simply advis- ing them to sail west along a certain latitude until they bumped into their destination, as would be the case with latitude sailing. Now let us look at Columbus's ability at celestial sights, which is a requirement for latitude sailing. His first recorded attempt at using a quadrant to establish his latitude was on 2 November when he was off the northern shore of Cuba. This sadly erroneous sighting put him on the latitude of Cape Cod. Even so, Columbus failed to recognize this gross error and instead con- cluded that he was not on Cipangu but on the mainland of Cathay. Morison thinks that on this occasion, Columbus mistook Alfirk for Polaris, but I believe James Kelley has the more logical answer in Columbus reading the tangent scale instead of the direct declination scale. In either event, it illustrates Columbus's serious incompetence in celestial navigation. Columbus tried the quadrant again on 20 November and came up with the same deplorable result of 42 degrees north latitude, but this time he realized that something was wrong and blamed in on the quadrant, which he said was broken and needed repair. How can a quadrant be broken when it has only one moving part and that part is a string with a weight on the end? Later at Moustique Bay in Haiti, Columbus made another celestial observation and found the latitude to be 34 degrees north when he was actually about 19 degrees 55' north. This time, Morison thought that Columbus mistook Er Rai, a star in the constellation Cepheus, for Polaris, but I doubt that we will ever know the real reason for his poor reading. All of this illustrates that Columbus's celestial navigation was sadly lacking (although his ego refused to let him admit it). Thus he would have depended on his dead reckoning from a known position (such as Hierro) for establishing his latitude and position. Columbus's mistrust of celestial observations and his complete reliance on dead reckoning are forcefully illustrated in the return voyage of the Nina. On Sunday, 3 February, he eye- balled the north star and declared it to be very high as on the latitude of Cape St. Vincent. Then on 10 February, after sailing due east for seven days, he placed his position west and on the same latitude as Casablanca in Africa. This latitude position is over 200 nautical miles south of Cape St. Vincent and thus would emphatically show that Columbus was relying on his dead reckoning and was disregarding, or certainly placing little faith in, his celestial observations. With such a preponderance of evidence showing Columbus's constant use of dead reckoning navigation, together with his demonstrated inability to use or to trust celestial observation, we can only conclude that Columbus used dead reckoning and not latitude sailing to navigate the Santa Maria from Gomera across the Atlantic to his landfall on Guanahani. ARNE MOLANDER'S RESPONSE TO DOUGLAS PECK In his defense of the dead reckoning rationalization, Douglas Peck makes the following statements, which, in my opin- ion, are erroneous and misleading: - "every change of compass heading and distance"--Columbus wanted to know both coordinates as accurately as possible at all times, whatever his method of navigation. He most definitely would not have serenely sailed at 28 degrees north latitude until he - "bumped into his destination," while carefully monitoring this latitude by latitude sailing. He needed these distanc- es for his chart longitudes, possibly also measured directly by lunar distance methods. - "his sole reference to Polaris"--While it is true that the Las Casas abstract does not describe how Columbus maintained latitude, neither does it explain how he estimated his longitudinal distances and velocities. Perhaps the original log contained these details, although accurate piloting techniques were then closely-held secrets. We do know that his celestial references were essential for LS, but not for DR. - "that these learned men had any part in the navigation"-- When Henry the Navigator established his navigation school at Sagres, his aim was to extend Portuguese exploration down the coast of Africa, not to enlighten astrologers. Does Peck believe that Portuguese progress was estimated by distance traveled rather than by direct altitude observa- tion? - "vessels on the second, third, and fourth voyages"--On his third voyage, Columbus - "decided to proceed further always directly westward, in a straight line for Sierra Leone, with the intention of not changing my course up to the point where I thought land would be found." Clearly, in this instance, he was latitude sailing across the Atlantic. Admittedly, the second and fourth voyages were both by DR from the Canaries to Dominica and Martinique. His second voyage was one of history's greatest navigational achievements because he managed to find the shortest (that is, safest) route to the New World by combining Arawak sketches with his own maps. Even with DR, he surely was anticipating Alonso de Chaves's later instruction for this west-by-south route to the Indies. The royal pilot warned sixteenth-century sailors continually to "enmendando su camino con la altura," and run directly west (that is, LS) if they "should arrive at the latitude of 14 or 15 degrees. - "Columbus's ability at celestial sights"--We all owe thanks to Jim Kelley (no advocate of LS!) for demonstrating that each of the three "wild" latitude measurements actually match the tangents for those elevation angles. I do not know whether it was common practice for pilots to read the quadrant's tangent scale rather than the angle, but the readings surely confused Las Casas and opened the door for libelous navigational commentary. - "Columbus's mistrust of celestial observations"--Although artfully disguised on Morison's route map, Columbus correct- ly made his only return course change at the Cape St. Vin- cent latitude. Once there, he sailed due east for only four days before piloting disagreements disrupted his LS course. He actually spent the next two days steering generally [south of east] in the direction of Casablanca. Peck's "due east" sail on Casablanca's "latitude" is without foundation. In conclusion, Van Bemmelen's isogonic contour guess for 1500 is the foundation for all DR rationalizations. Unfortunate- ly, since all his speculation presumes a Watlings Island land- fall, Morison forgot that changes would shift the landfall by some forty miles in the intervening eight years. Similarly, the National Geographic Society's elaborate simulation overlooked Van Bemmelen's crude contour scaling of 2000 miles per inch, and everyone accepted McElroy's unsubstantiated smoothing and extrap- olation of these imaginary contours! Inadequate analysis has hopelessly mired the Columbus landfall search in the southern Bahamas rather than focusing on Columbus's LS navigation to Northeast Providence Channel. This northern entrance to the New World lies at the 26 degree north latitude accurately described in Columbus's 1493 letter and reaffirmed by Ponce de Leon in 1513. DOUGLAS PECK'S RESPONSE TO ARNE MOLANDER At first glance, Arne Molander's argument sounds convincing, sprinkled as it is with quotes from renowned authors and contain- ing a learned discourse on the ease with which Columbus could have maintained his latitude by celestial observations. But a serious scrutiny of these quotes and the relevance of the celes- tial navigation method makes his argument fall apart. Molander asserts that Morison supports his theory. This just is not so! Morison did indeed say that Cabot and Cartier used the "time honored" latitude sailing by sailing west on a high latitude to hit Cathay or to find a passage to Cathay; but they did this by sailing a DR compass course and only confirmed the latitude of their landfall on land or in a quiet anchorage with a quadrant or astrolabe at the end of the voyage and not by using the celestial "latitude sailing" method at sea proposed by Molander. Cabot and Cartier were both obviously proficient in the use of the quadrant and astrolabe, but as I have shown in my essay, Columbus certainly was not. In his log, Cabot noted a 22 1/2 degree variation in the compass in mid-Atlantic (to correct his DR navigation) and only mentions latitude at the end of the voyage when taking sights on both Polaris and the meridional altitude of the sun at Cape Degrat, Newfoundland, and stated the latitude was the same as Dursey Head, Ireland. In his voyages of 1534 and 1536 (over forty years after Columbus), Cartier gave a number of fairly accurate latitude measurements indicating his skill with the astrolabe, but always on land or in a quiet anchorage, never at sea. I cannot argue with the fact that a navigator with Molander's knowledge of celestial navigation can determine his latitude at sea by observation of the elevation of certain circumpolar stars. But to say that Columbus used this highly technical navigation method for his 1492 crossing is pure fiction and can be supported only by conjecture and not by fact or logic. Now to refute Molander's three reasons why Columbus must have used celestial latitude sailing: The first speaks of a rescue mission in case Columbus ran into trouble. This again is pure fiction. Where in our study of history can we find any mention of proposed rescue missions for Dias, Vasco da Gama, Magellan, Cabot, Verrazzano, et al? Why would Columbus even think about a rescue mission? The second is the political reason that would limit Columbus's landfall to north of the twenty-seventh parallel. Columbus obviously did not worry about this prohibition (meant to protect the rights of the Portuguese in their African trading posts) since the first thing after making landfall, he struck off south to Cuba and Hispaniola, which are many hundreds of miles south of the twenty-seventh parallel. The third was Columbus's proposal to make a new chart showing latitudes and longitudes. He no doubt did make such a chart, but he did it by dead reckoning form his departure point in the Canaries. The fact that he mentions the word "latitude" is hardly an argument for Columbus's using the involved and complicated celestial latitude sailing method Molander proposes. As to the impressive quotes from "independent experts," Eva Taylor wrote a broad history of technology; G. J. Marcus wrote a book about the early Viking landfalls; Tim Severin has written about the ancient Greek voyages; and Thor Heyerdahl wrote about the pre-Columbian Polynesians and Egyptians. But because these respected writers may be "independent experts" in their own fields does not mean their expertise spills over into other fields and gives their unsubstantiated remarks about Columbus's navigation any more weight than some "non-independent expert" who has studied the subject in depth. Clearly, there is no hard evidence based on fact to show that Columbus used celestial latitude sailing to arrive at a landfall in the northern Bahamas, but there is ample and overwhelming evidence to show that he used a compass and elapsed time (DR navigation) to establish his position at sea and on the island landfalls. Permission granted by publisher.