1. The most commonly accepted distances of the 1492 voyage are 3,066 nautical miles from the last sight of land in the Canaries to landfall in America, or 3,117 nautical miles from the port of departure: Morison, S.E., Christopher Columbus: Admiral of the Ocean Sea (London, 1942), 221.Google Scholar

2. This paper discusses Columbus' purported voyage to Mina in Guinea and in particular the subsequent return voyage. The significance of the return voyage appears to have been first maintained, half a century ago, in various publications by the Portuguese nautical historian, Admiral Gago Coutinho, who, for instance, produced in 1942 a map claiming Columbus' return on the volta da Mina: Coutinho, Gago, A nàutica dos descobrimentos (2 vols.: Lisbon, 1951–1952), 1:154–57Google Scholar, 2: 26-28, 196, map opposite 296. The map was borrowed or copied by several later writers on Columbus, mainly Portuguese writers—the most recent version I have seen being in Marques, Alfredo Pinheiro, Portugal and the European Discovery of America (Lisbon, 1992), 38Google Scholar, where the caption notes that the Mina voyage was Columbus' “first major oceanic voyage.” But the full significance of the Mina voyage was ignored in general biographies and studies of Columbus. In the most recent full-length study of Columbus the visit to Mina is dismissed in half a sentence: Fernàndez-Armesto, Felipe, Columbus (Oxford, 1991), 18Google Scholar (in keeping with an earlier work, Fernàndez-Armesto, Felipe, Before Columbus (Oxford, 1989)Google Scholar, which combines an authoritative appreciation of the Atlantic ventures of Italians and Spaniards with a consistent depreciation of Portuguese ventures). As regards the return voyage by the volta da Mina, Gago Coutinho merely predicated the existence of the volta at the appropriate dates and offered virtually no contemporary evidence, while his interest centered on the value to Columbus of his pre–1492 acquaintance with the winds, currents, and other sea conditions of the central Atlantic. The present paper re-examines the evidence and makes a rather different point, the sheer length of the return voyage.

3. The references occur in the manuscript notes (“postils”) added in poor Latin to books owned by the Columbus brothers. The four postils include references to Mina, as quoted below, the first three references mentioning a Columbus presence at Mina. These particular postils are found in two books printed in 1477 and in either 1480 or 1483, respectively. It is unclear when the postils were inserted and they may not have been all added at the same date, but the only dates given within the postils of these books are 1481, 1485, 1488, and 1491, and it appears to be generally supposed that the books were first read and at least most of the postils added before 1492: Fernàndez-Armesto, , Columbus, 39–41.Google Scholar

(a) sub linea equinociali perpendiculariter est castrum Mine serenissimi regis Portugalie, quem vidimus. [Directly under the equinoctial line is the castle of the Most Serene King of Portugal, which we have seen.]

(b) Zona Torida. non est inhabitabilis, quia per eam hodie navigant Portugallenses, imo est populatissima, & sub linea equinoxialis est castrum Mine serenissimi regis Portugalie, quem vidimus. [Torrid Zone. It is not uninhabited, because the Portuguese regularly navigate within it [sc. to trade], indeed it is densely populated, and under the equinoctial line is the castle of Mina of the Most Serene King of Portugal, which we have seen.]

(c) …a parte australi & septentrionali habitant gentes sine numero, nec impedit maximum calorem. & sub linea equinotiali, ubi dies semper sunt horarum . 12., habet castrum serenissimus rex Portugalie, in quo fui, & inveni locus temperatus esse. [In the northern and southern parts live innumerable people, and this is not prevented by the greatest heat, and under the equinoctial line, where the days are always 12 hours long, the Most Serene King of Portugal has a castle, in/at which I was, and I found the place to be temperate.]

(d) … rex portugalie misit in guinea anno domini 1485 magister Ihosepius fysicus eius et astrologus [ad com]piendum altitudinem solis in totta guinea … et renunciavit … me presente quod … invenit se distare ab equinoxiali gradus .V. minute in insula vocata de los ydolos … et … rex misit in guinea in alliis locis postea …et semper invenit concordari cum ipso Magister Iosepio quare sertum habeo esse castrum Mine sub linea equinoxiali. [The king of Portugal in 1485 sent to Guinea Master Josephius, his doctor and astronomer, in order to find the altitude of the sun throughout Guinea … and he reported … when I was present … that he found the Ilhas dos Idolos to be 5° distant from the equator … and … the king afterwards sent to other places in Guinea … and there was always found agreement with Master Josephius, so that I believe it certain that the castle of Mina is under the equinoctial line.] Cited from Cesare de Lollis, Scritti di Cristoforo Colombo (3 vols.: Genoa, 1892; Rome, 1894), 2:294, 375, 390, 369.

The “we” (vidimus “we have seen”) in the first two references is very uncommon in the postils (it occurs only once more: De Lollis, Scritti, 2: 292) and contrasts with the “I” of the third postil (which, with “me,” is also very uncommon). The “we” is generally assumed to be a royal “we” and—partly because of the use of “I” in what appears to be another version of the same reference—is accepted as indicating only Christopher. But a joint voyage to Mina with his brother Bartholomew, a mapmaker in Lisbon, might be an outside possibility. Bartholomew's association with Christopher in searching out information on earlier Atlantic discoveries was stressed in Bartolomé de las Casas, Historia de las Indias, ed. Agustín Millares Carlo (3 vols.: Mexico City, 1951), 1: 146 [lib. 1, cap. 27]. Las Casas stated categorically that one of the postils he had occasion to cite was written by Bartholomew, some scholars have argued that other postils were by Bartholomew (see Fernàndez-Armesto, Columbus, 200n22), and it seems almost certain that the final postil cited above was not from the hand of Christopher—for the significance of this postil, see note 40 and Appendix A. But even if the first two postils cited above were written by Bartholomew, the “we” may have been merely an orotund reference to his brother. Las Casas, in a confirmatory reference (apparently based on other than a reading of the postils), specified that it was indeed Christopher who visited Mina: “… dice assi el Almirante: “Yo estuve en el Castillo de la Mina del Rey de Portugal, que està debajo de la equinoccial, y asi soy buen testigo que no es inhabitable como dicen.” Casas, Las, Historia, 1:32 [lib. 1, cap. 3].Google Scholar Hereafter I shall assume that, if any Columbuses visited Mina, it was at least Christopher.

Whether Columbus simply “saw” Mina, or was “in” the castle, is of no significance in the present discussion. It is virtually certain that on any voyage to Mina at that period Columbus would have had to travel on a Portuguese vessel—hence, he might have been allowed within the castle, or alternatively might have observed it from the anchorage without being allowed to go ashore, a procedure envisaged by some of the later regulations and perhaps especially to be applied to a foreign visitor. (For regulations of 1509 controlling the movements of a ship's crew at Mina and only allowing them, apart from the senior officers, to go ashore on set occasions to a market on the beach and therefore apparently not into the fort, see Faro, Jorge, “Estevão da Gama, capitão de S. Jorge da Mina e a sua organização administrativa em 1529,” Boletim Cultural da Guiné Portuguesa 12 (1957), 414–17Google Scholar; and Blake, J.W., Europeans in West Africa, 1440-1570 (London, 1942), 105n1.Google Scholar But however treated on arrival, Columbus would have reached the locality of the castle.

4. The date of 1485 for the voyage to Mina, within an assumed range of 1482-85, is put forward as most likely in Fernàndez-Armesto, Columbus, 31, but the argument is speculative and unconvincing. That Columbus was one of the party that founded the castle in 1482 was suggested by Mori son in 1940, and this unevidenced and implausible opinion was followed by certain later writers, but Morison elsewhere presented it only as an alternative possibility: Morison, S.E., Portuguese Voyages to America in the Fifteenth Century (Cambridge, Mass., 1940), 72Google Scholar; idem., Admiral of the Ocean Sea (2 vols.: London, 1942), 1:41.

5. See Catz, Rebecca, Christopher Columbus and the Portuguese, 1476-1498 (Westport, 1993), chapter 2.Google Scholar

6. See Hair, P.E.H., “Columbus from Guinea to America,” HA 17 (1990), 113–29Google Scholar; and López, José Luis Cortés, “El tiempo africano de Cristóbal Colón (Precisiones para su biografia),” Studia historica [Salamanca] 8 (1990), 313–26Google Scholar; each article independently discusses whether Columbus sailed to Guinea more than once. Fernàndez-Armesto suggests that the visit to Mina is confirmed by Columbus' later use of “the Portuguese argot of the coast,” but does not explain the reference, which I do not understand: Fernàndez-Armesto, Columbus, [xxiii].

7. For details of this calculation and the evidence see Hair, P.E.H., ed., The Founding of the Castello de São Jorge da Mina (Madison, 1994), 6.Google Scholar The Portuguese vessels visited one or both of the two ports on the coast, one of which was the locality where the fort was sited in 1482, and this locality was visited by at least a proportion of these ships. Castilian vessels also visited the coast in the 1470s, but the authorities ordered the visits to cease after peace was made with Portugal in 1479-80. Castilian visits should therefore have stopped before the castle was built, a sequence which would remove any possibility that Columbus traveled on a Castilian ship. However, it cannot be entirely ruled out that occasional Castilian vessels, acting illegally, may have reached the coast and sighted the castle during the early 1480s, even although this is unevidenced. But since at this period Columbus was, as far as we know, still working within the Portuguese sphere, his association with a voyage which was not only forbidden by Castile but which, if intercepted by Portuguese vessels, might lead to its crew being executed (as threatened by Portuguese legislation in 1480), is highly unlikely.

8. For the Castilian voyages, see Hair, , Founding of Mina, 6, 8–9.Google Scholar

9. de Pina, Rui, Crónica de el-Rei D. João, ed. de Carvalho, Alberto Martins (Lisbon, 1950), 8–9 [cap. 2].Google Scholar

10. It is possible, although unlikely, that he sailed to Guinea not from Lisbon but from the Madeira group.

11. [Fosse, Eustache de la], “Voyage à la côte occidentale d'Afrique, en Portugal et en Espagne,” ed. Foulché-Delbosc, R., Revue Hispanique 4 (1897), 177–81Google Scholar, or Escudier, Denis, ed., Voyage d'Eustache Dela fosse (Paris, 1992), 14–26.Google Scholar The outward voyage took from 2 October to 17 December 1479.

12. The first ship on which the trader returned was the one on which he went out to Mina (described as “ma carvelle”), since after being captured it had been “bought as booty” by Diogo Cão (de la Fosse, , “Voyage,” 183Google Scholar; Voyage, 30).

13. Eustache de lar fosse, “Voyage”, 184, 191Google Scholar; Voyage, 32, 50.

14. As early as the 1440s, a voyage from Senegal successfully reached Portugal despite the ship being manned only by a handful of inexperienced youths who knew no more than to point the ship “north and a little east” (chapter 86 of de Zurara, Gomes Eanes, Chronique de Guinée, ed. Bourdon, L. [Dakar, 1960], 239–41)Google Scholar; or (abbreviated version, introduction by J. Paviot), Chronique de Guinée (1453) [Paris, 1994], 242–44).Google Scholar The meager record implies that no attempt was made to follow the coast, and at this date the Cape Verde Islands had not yet been discovered. If, as has been argued, the course was actually north and then east, this suggests that such a route home, by a high-seas sweep (volta do mar largo), was already a regular practice (ibid., 240n6 or 244n1). Other arguments for early mid-Atlantic voltas turn on the discovery of Madeira and the Azores, alleged marking of the Sargasso Sea on early maps, and the statement of Diogo Gomes that in the 1450s, when a contrary wind prevented him from sailing direct to Lisbon from Madeira, he sailed there instead via the Azores (Monod, T., Mauny, R. and Duval, G., eds., De la première découverte de la Guinée récit par Diogo Gomes (fin XVe siècle) (Bissau, 1959), f. 282vGoogle Scholar; Coutinho, Gago, Nàutica, 1: 154–57Google Scholar; Waters, David, “Columbus' Portuguese inheritance,” Mariner's Mirror 78 (1992), 391–92.CrossRefGoogle Scholar

15. Waters, David W., “Reflections Upon Some Navigational and Hydrographic Problems of the XVth Century Related to the Voyage of Bartolomeu Dias 1487-88,” Revista da Universidade de Coimbra 34 (1988), 310Google Scholar (= série separatas 201, Centra de Estudos de História e Cartografia Antiga, Lisbon, 1988), citing da Mota, Avelino Teixeira, A evolução da ciência nàutica durante os séculos XV-XVI na cartografia portuguesa da época (Lisbon, 1961), 7Google Scholar; also see Waters, , “Inheritance,” esp. 391–92.Google Scholar For the various voltas see the Atlantic maps in Waters, , “Reflections,” 296, 333Google Scholar (taken from de Albuquerque, Luís, Os descobrimentos Portugueses [Lisbon, 1985], figure 70)Google Scholar and Waters, “Inheritance,” figure 2; Coutinho, Gago, Nàutica, 1: pp. 336Google Scholar; da Mota, Avelino Teixeira, “A viagem de António de Saldanha em 1503 e a rota de Vasco da Gama no Atlântico Sul,” Grupo de estudos de história marítima—memórias (Lisbon, 1971)Google Scholar (= série separatas 64, Agrupamento de Estudos de Cartografia Antiga, Lisbon, 1971, 9–63Google Scholar). In a document of 1514 there is a reference to a ship from São Tomé making a “volta da Guiné” towards the Azores and being “a good 150 leagues from land” when broadly in the latitude of the Cape Verde Islands, therefore probably at that distance from those islands, making the position some 1,000 miles out from the African coast: de Albuquerque, Luís and Santos, Maria Emília Madeira, eds., História geral de Cabo Verde: corpo documental (2 vols. to date: Lisbon, 1988–1990), 2:290.Google Scholar

16. “Guinea tack” and “Mina tack” are the English terms employed in da Mota, A. Teixeira, Portuguese Navigation in the North Atlantic in the Fifteenth and Sixteenth Centuries (St. John's, Newfoundland, 1965), 11.Google Scholar

17. Gago Coutinho and most later writers on the history of navigation suppose that once Portuguese ships had reached Mina some of them must have returned on a volta more or less immediately. Rather more cautiously, Teixeira da Mota stated that “the Portuguese were quick to recognize the effects of these conditions” of winds and currents, and noted “the speed with which this technique was discovered,” but did not produce specific evidence for this last assertion or suggest an exact date: da Mota, Teixeira, “Portuguese Navigation,” 10.Google Scholar They base this supposition on the belief that the volta da Guiné from coasts further west and north had long been practiced and that it only needed to be gradually extended to become the volta da Mina. But it seems more likely that the earliest visitors to the Costa da Mina chose to return the way they had come—as was possible, albeit slow and difficult—and that only later did ships venture to explore the high-seas route. One reason for caution may have been that whereas further west the volta began by striking out to west and northwest, the volta da Mina demanded an initial stage due south and across the equator, a more uncertain venture. Further, since the contrary currents are more intensive to the east of Cape Palmas, the need for a volta would not have been as strongly felt until exploration had passed this point, which was apparently in the late 1460s. Therefore the earliest vessels to reach the Costa da Mina in the 1470s may not have considered a volta.

18. de Palencia, Alonso, Cronica de Enrique IV, ed. and trans, [from Latin] y Melia, A. Paz (5 vols.: Madrid, 1906–1909Google Scholar; reprinted in 2 vols.: Madrid, 1973-75), dec. 3, lib. 25, cap. 5; lib. 26, caps 5-6; Torre, Antonio de la and Fernàndez, Luis Suàrez, eds., Documentos referentes a las relaciones com Portugal durante el reinado de los Reyes Catoilicos (3 vols.: Valladolid, 1958–1963), 1: item 51.Google Scholar

19. Waters, , “Reflections,” 58.Google Scholar Note also the following statement: “Only ships with lateen sails could progress down the coast, as was the case with the voyages of Diogo Cão and Bartolomeu Dias, whereas it was essential for ships with round sails (de pano redondo)—like those of Vasco da Gama—to sail first to the southwest, to catch the prevailing winds of the southern hemisphere…” (translated from da Mota, Teixeira, “Viagem,” 7Google Scholar). This implies that the choice of vessels confirms Portuguese knowledge of the wind system, at least by the 1490s. In earlier studies it was argued, particularly by Jaime Cortesão in support of his theory of secret Portuguese voyages, that, whereas by 1497 the South Atlantic wind system was known, in 1487 it was not, the proof being that Bartolomeu Dias sailed coastwise on most of his journey south: see Domingues, Francisco Contente, “Colombo e a política de sigilo na historiografia portuguesa,” Revista Mare Librum 1 (1990)Google Scholar (=série separatas 232, Centra de Estudos de História e Cartografia Antiga, Lisbon, 1992), 105-16, esp. 107).Google Scholar But Dias went south coastwise because he was exploring part of the coast and, although he returned via Príncipe and Mina and not directly to Portugal, there were many reasons for this other than ignorance of the possibility of a high-seas return—for instance, the need to call in at land to obtain food, firewood, and water.

20. While there is no firm evidence of a volta by this date, the difficulties of returning coastwise were certainly appreciated, if we can believe an anecdote recounted by a chronicler fifty years later. According to Resende, João II gave orders that when the ships of the 1482 fort-building expedition reached Mina the round ships carrying material were to be destroyed, on the grounds that these vessels were unable to return because of the currents—that is, they had difficulty in tacking: de Resende, Garcia, Chronica … del Rey Dom loan II (Coimbra, 1798), cap. 25, p. 31Google Scholar, translated in Blake, , Europeans, 71.Google Scholar However, according to the same source, on another occasion the king publicly asserted that round ships could not sail to Mina on account of the currents, but when challenged by an experienced pilot admitted that his assertion was bluff designed to discourage enemy voyages—an admission which suggests that his destruction of the round ships was motivated as much by political as by navigational considerations (Resende, Chronica, cap. 101). Teixeira da Mota interpreted the latter anecdote as indicating that “ships with square sails” were returning from Mina on the volta, but even if this interpretation is correct, the anecdote may well relate to the the early 1490s, hence it is not, as suggested, conclusive proof of the speedy adoption of the volta: da Mota, Teixeira, “Portuguese Navigations,” 10–11.Google Scholar

21. de Barros, João, Asia … Primeira década, ed. Cidade, Hernani (4 vols.: Lisbon, 1945), 1:254–55Google Scholar [déc. 1, liv. 6, cap. 7].

22. Blake, , Europeans, 126n2.Google Scholar

23. Casas, Las, Historia, 1: 69 [lib. 1, cap. 13]Google Scholar; Keen, Benjamin, trans, and ed., The Life of the Admiral Cristopher Columbus by his son Ferdinand (London, 1960), 52.Google Scholar

24. Unfortunately “Vicente Dias” was a common name. Without an unlikely extension of his lifespan our man cannot have been the same as the Vicente Dias whom Zurara credits with the discovery of the Cape Verde Islands, apparently in 1445, or the Vicente Dias who was a prominent shipper and shipowner in the Cape Verde Islands in the 1510s: de Albuquerque, Luís and Santos, Maria Emília Madeira, eds., História geral de Cabo Verde (1 volume to date: Lisbon/Praia, 1991), 22-29, 376-77, 390Google Scholar; Albuquerque, and Santos, Madeira, História, 2:96et passim.Google Scholar

25. The sources for this voyage mention unusually circumstantial evidence (which appears not to have been adequately researched to date). Dias is said to have obtained a royal license for the search and two Genoese backers are named, Lucas and Francisco de Cazana, who operated respectively from Terceira and Seville. Extant documents do record that in 1462 a licence to search for an island northwest of the Canaries and Madeira was given to another Tavira seaman, and that in 1486 the captain of Terceira was awarded any island or mainland he was able to discover: Marques, João Martins da Silva, Descobrimentos Portugueses (3 vols.: Lisbon, 1944–1971), 3:34-35, 317, 326–29.Google Scholar

26. That there was direct trade at this date between Guinea and the Azores seems unlikely, therefore the Tavira seaman was most probably calling in at the Azores on a return voyage to Portugal. By 1518, however, a “return voyage from Guinea to Terceira” is recorded, in this case from western Guinea via the Cape Verde Islands: Albuquerque, and Santos, Madeira, História, 2: 300.Google Scholar Since Dias was in contact with a Genoese merchant on Terceira, he was probably picking up Azorean products for conveyance to Lisbon. In these circumstances a direct route from Guinea to the Azores seems more likely than the roundabout route by Madeira (although in different circumstances an earlier Guinea-Madeira-Azores-Lisbon voyage is claimed, see note 14 above).

27. This is accepted in Cortesão, Jaime, História dos descobrimentos Portugueses (3 vols.: Lisbon, 1979), 1:137Google Scholar, where the episode is discussed more casually. As further evidence of the early existence of the volta da Guiné Cortesão cites only a 1501 document relating to a ship carrying malagueta pepper, hence presumably coming from the Malagueta Coast, which sailed to the Azores and then Portugal; but this is surely a late date, not an early one.

28. I have argued elsewhere that Columbus visited the Malagueta Coast, probably at River Sess, and that this may indicate a second voyage to Mina (Hair, “Columbus”). But if he did not return on the volta da Mina, the call at the Malagueta Coast could have been on the return voyage from his only visit to Mina. The outside possibility that he sailed to Mina not from Lisbon, but from Madeira, might also involve his returning on a vessel that took the coastwise route on another such possibility, that he wished to return to Madeira.

29. If Columbus did indeed return on the volta da Mina it would have carried him south of the equator for the first and, as it happened, the only time in his career. The Columbus brothers believed, however, that Mina was located on the equator instead of actually at 5°N, believing this at least at the time that they wrote three postils (see note 3). They were apparently not the only persons in the Portuguese domain to displace Mina in the early years of the fort. In 1485 an official address to the pope by a special envoy from the King of Portugal spoke of the castle at Mina being “beyond the equinoctial zone” (ultra equinoccialem plagam): Rogers, Francis M., The Obedience of a King of Portugal (Minneapolis, 1958), 47.Google Scholar Since an error about its location might be thought to weaken the Columbus claim to have visited Mina, an explanation of the error is relevant. However, as is generally the case with issues relating to the vagaries of Columbus' career, the explanation requires a lengthy and somewhat tortuous discussion; see the Appendix above.

30. The supposed Iceland voyage is discussed affirmatively in Quinn, D.B., “Columbus and the North: England, Iceland and Ireland,” William and Mary Quarterly 3/49 (1992), 278–97.CrossRefGoogle Scholar

31. In the Atlantic, the previous longest, non-stop, high-seas voyages were presumably those in the north, from Britain and Ireland to Iceland, from Norway and Denmark to Iceland, and from Iceland to “Vinland,” each being between 800 and 1,200 miles. If at any stage there were direct voyages from Bergen to Greenland, or even to the American coast, these would have been about 1,500 and 2,000 miles respectively. Elsewhere in the world and before the volta da Mina, the longest non-stop regular voyages were probably those across the Indian Ocean of “Arab” vessels (the Chinese voyages in that ocean followed coasts and made frequent stops), the length of the voyages which did not call at mid-ocean islands being between 2,000 miles and 3,000 miles. Polynesian voyages in the Pacific may sometimes have achieved over 3,000 miles non-stop but were hardly regular. It is therefore almost certain that the Portuguese voyages on the volta da Mina were the longest regular non-stop voyages in the history of the world up to that date. But they were soon overtaken by the even longer non-stop voyages of the Carreira da Índia.

32. It is possible that some of these Castilian sailors had been at the Costa da Mina on the fleet of eleven vessels which in 1479 was captured by the Portuguese. The captured ships and crews, presumably with Portuguese commanders, were brought back to Europe by the Portuguese fleet, and the surviving Castilian sailors were subsequently ransomed. The brief and vague contemporary account of this operation speaks of the ships reaching “the island0 before arriving at Lisbon: de Toro, José López, Cuarta década de Alonso de Palencia (2 vols.: Madrid, 1970)Google Scholar, lib. 33, cap. 5 =1:75-78, in translation 2:91-95). Since “the island” probably means Grand Canary, where Portuguese and Castilian fleets were also battling, and since the returning Portuguese feared Castilian interception at sea, it would seem that on this occasion use was not made of the volta da Mina or the volta da Guiné. Whether Castilian ships sailing singly or in small groups to Mina before the peace of 1480 ever returned by the volta da Mina is not known. However, even if Castilian vessels never employed this volta—and it may not actually have been known in the 1470s—it is likely that before 1492 it had been experienced by a number of Castilian sailors. Portuguese vessels normally included in their crews a number of Andalusians, hence Castilian sailors must have participated in the pre-1492 Portuguese return voyages from Guinea. In any case, it cannot be doubted that the southern ports of Iberia, Portuguese and Castilian, shared marine information.

33. It is therefore difficult to know what to make of Columbus' final remark (as quoted by Las Casas) in his Instructions for his third voyage: Casas, Las, Historia, 2:498 [lib. 1, cap. 130].Google Scholar The plan was to sail south from the Cape Verde Islands to below the equator before turning west. The plan was misconceived and did not operate, but Columbus allegedly commended it on the grounds that “I believe it to be a route never before followed and the sea quite unknown” (esta mar muy incógnita). The “unknown sea” was, at least in part, that through which the volta da Mina passed.

34. A handful of medieval travellers, most famously Marco Polo, in voyages between India and the Far East or to the “Spice Islands” had in fact sailed across the equator and noted populations to the south, and one or two had reported the loss of the North Star as a clue to their position, but apparently this information either did not reach western scholars or did not convince them. See Phillips, J.R.S., The Medieval Expansion of Europe (Oxford, 1988), 195.Google Scholar

35. Duarte Pacheco Pereira, Esmeraldo de situ orbis, various editions, liv.1, cap. 7; liv. 2, caps 5, 11.

36. Ibid., liv. 2, cap. 11.

37. Ibid.

38. Barros, Décadas, déc. 1, liv. 4, cap. 2.

39. See Duarte Leite, História dos Descobrimentos, with later critical notes by Vítorino Magalhães Godinho (3 vols.: Lisbon, 1958-61), 1: 397-410. Leite's view in the text contradicted by Magalhães Godinho in the notes.

40. Earlier Portuguese views about the latitudes of the Guinea coast are uncertain. The early maps did not show latitudes. Diogo Gomes's statement that the equator lay at Cape Verde (actually 14°43'N) may represent either the erroneous contemporary view when he sailed the Senegambian coast in the 1450s, or else his confused recollection when narrating his account in old age, in the 1480s or 1490s—perhaps the latter since his learned editor marginated that the statement was untrue: Monod, et al., Première découverte, f. 274.Google Scholar In the 1450s Cadamosto noted that he still observed the Pole Star at the mouth of Gambia River and in 1461 a Portuguese pilot observed it much further east, near Sherbro Island, while Cadamosto confirmed that he was still north of the equator by noting the unequal length of day and night: Leporace, T.G., ed., Le navigazioni Atlantiche del Veneziano Alvise da Mosto (Venice, 1966), 86, 122Google Scholar; English translation, Crone, G.R., The Voyages of Cadamosto (London, 1937), 61, 82.Google Scholar Thus, since it must have been obvious that the Iles de Los were well north of Sherbro Island, the 1485 calculation, claiming a latitude of only 5°N for the former, may well have struck Guinea pilots as of doubtful accuracy—but apparently not Columbus.

41. Lollis, De, Scritti, 2:407.Google Scholar

42. da Mota, Avelino Teixeira, “Bartolomeu Dias e o valor do grau terrestre” in Actas, Congresso Internacional de História dos Descobrimentos (2 vols.: Lisbon, 1961), 1:separately paginated.Google Scholar

43. Fernàndez-Armesto, , Columbus, [xxiii], 31Google Scholar, however, appears to accept that the observations were taken on the Mina voyage, which he also relates to the 1485 visit to Guinea of the Jewish astronomers—an unlikely concatenation. In this context, to be firmly discounted is the claim of a very much later source that an astrologer accompanied the 1481 expedition and at the founding of the castle worked out the latitude of Mina, or a modern version of this fiction which states that the leader of the expedition was “the first mariner to use the sea-astrolabe on a voyage down the west coast of Africa:” da Silva, Manoel Telles, De rebus gestis Joanni II (Lisbon, 1689), 152Google Scholar; Leite, , Historia, 1:399–400Google Scholar; Howse, Derek, “Navigation and Astronomy: the First Three Thousand Years,” Renaissance and Modern Studies 30 (1986), 63n5.CrossRefGoogle Scholar

44. This paper arose out of a 1992 discussion at Oxford with Felipe Fernàndez-Armesto, and I am indebted to David Quinn and David Waters for corrections to an earlier version.