Chart-making was an important branch of study at Sagres. So few and rare were sea-maps then that one was never seen in England until 1489. To the collection of information in this direction, and the improvement of nautical methods, Prince Henry and his aids applied themselves most diligently; but he died before much had been accomplished. Nautical studies went on, however, under the next king, John II, for whom Martin of Bohemia, the foremost astronomer of his time, devised a form of the astrolabe for use on shipboard, increasing accuracy in finding latitude.
It was with no better instruments than these (and sand-glasses in place of chronometers) as guides over chartless and unsounded seas that the way was found to India and to America, and the globe was circumnavigated; and that the same thing might be done again is shown by the fact that only last year (1897) a vessel, which had barely escaped destruction in a storm and lost all her instruments in the mid-Pacific, was brought safely into San Francisco by observation of the stars and “dead-reckoning” alone.
But Prince Henry (for I have run ahead of my story again) was not content to study and teach on land alone. He was fired with the ardor of discovery and conquest likely to augment Portugal’s wealth and influence in the East. Expedition after expedition was sent southward, and in 1435 Henry’s ships finally passed Cape Bojador. Great was the wonder and rejoicing thereat, for it had always been taught by the monks that this cape was the end of the earth; but it was not until 1462 that the Cape Verd Islands and Sierra Leone were reached. Prince Henry had been dead since 1460, but the influence of his wise and untiring enthusiasm and work lived on, and inspired the king and people of Portugal to renewed efforts at solving that riddle of Africa that perhaps the Egyptian sphinx was meant to typify. By 1469 trade had been opened with the Gold Coast, and a few years later the mouth of the Congo was found.
These advances showed that there was nothing unnatural or fearful in the southern latitudes, as sailors had been taught to believe from time immemorial,—a superstitious dread which the old chart-makers long sustained by their habit of filling the empty sea-spaces on their maps with fearsome and wondrous monsters,—and therefore, in 1486, King John II sent Bartholomew Dias in two sail-boats—pinnaces of fifty tons each—with orders to go as far as he could; and this bold captain, passing the last known headland of the Guinea coast, sailed on and on, tracing the West African coast, and landing here and there to examine the swampy shores, to get fresh water, and to hoist the castellated banner of Portugal in token of possession before the wondering eyes of naked negroes. At length he was blown and buffeted for days and days in heavy storms, and at their close found himself far to the eastward of his former longitude, whereupon he fought his way on and sighted land which he rightly determined must be the southern extremity of Africa. This was in 1487. Returning to Lisbon toward Christmas of that year, he reported his experiences, and dwelling especially upon the rough time he had had in the south, proposed to style the point of the continent Cape of all the Storms; but King John, foreseeing great things to follow for his country, said, “No; we will call it the Cape of Good Hope”; and so it remains to this day—but all the storms remain about it, too!
PORTION OF A FIFTEENTH CENTURY SEA-CHART, BY TOSCANELLI.
Copied by permission of Messrs. Houghton, Mifflin & Co., from Justin Winsor’s “Narrative and Critical History of America.”
Now for some years previous to this time the monarchs of western Europe were much exercised over rumors of the existence somewhere in the Orient of an all-powerful and generally marvelous potentate styled (by them) Prester John, and reputed to be a conqueror of Asiatic, or perhaps African, infidels who later had become cut off from Christendom. The whole affair was a myth, probably arising from an indistinct knowledge of Abyssinia, whose negus afterward borrowed the title; but before this was realized popes and various “Catholic majesties” had sent embassies in search of Prester John’s court, some of which incidentally gained valuable information. Among the latter was Pedro Covilho, an emissary of Portugal, who, having failed to find Prester John in western India or Persia, made his way back to Egypt and Abyssinia, whence he sent home in 1486 or 1487 a report of progress that told John II some surprising news of the advancement of the Arabs of that part of the world in the sciences, and especially in those belonging to geography and navigation.
Covilho’s messenger was a Portuguese Jew, Rabbi Joseph of Lamego, who carried voluminous letters, one of which showed that Arabic mariners were then familiar with the whole length of the east coast of Africa, including Madagascar, and were perfectly well aware where it terminated at the south, and that there was no obstacle to passing around to the western side of the continent; and just at this interesting juncture Dias came sailing back in his pinnace to say that it was all true, for he had seen it.
Thus the sea-road was open to India and Cathay, and Portugal was eager to take advantage of it. She was then one of the leading powers of Europe, and the foremost one in colonial and commercial enterprise, striving to wrest from Genoa and Venice the supremacy in trade that they had so long enjoyed. Nevertheless almost ten years elapsed before the next expedition was sent southward to confirm Portugal’s possessions, and establish commerce with the Orient. John II had died, and Emmanuel the Fortunate reigned in his stead—a reign that has been called the heroic period of the nation’s history; and it must not be forgotten that “Little Portugal” was then so mighty that a year or so previously (May 4, 1493) the Pope (Alexander VI) had issued a bull in which he had divided, with intended equality, all undiscovered parts of the earth between Spain and Portugal, the former being given everything to the west, while to Portugal were reserved all future rights east of a certain north-and-south line.
The line of separation designated was the meridian of no variation of the compass-needle. The existence of such a line had been discovered by the same Christopher Columbus who was to thrill the world a few years later; but he did not know, what only experience developed, that this meridian was changeable, swinging many degrees east and then returning west in the course of two or three centuries. At that time the line seemed fixed some three hundred miles west of the Azores, and philosophers accounted for it later by a theory that it lay in the middle of the Atlantic because there it was subject to an equality of attraction toward both continents which held it steady. This was not true, but it was better than the less learned but more popular explanation of the magnetism of the compass—namely, that it was “an effluvium from the root of the tail of the Little Bear.” A year later, however (June 7, 1494), the treaty of Tordesillas, between Spain and Portugal, declared that the line of demarcation should be the meridian 370 leagues west of the Cape Verd Islands, or as nearly as possible in the center of the Atlantic. The supposition that there might be valuable lands within, that is, east of, that limit, inspired several of Portugal’s subsequent searchers.