A Disc on the Seabed of History: Vasco da Gama’s Astrolabe and the Beginning of Empire

The discovery of a late 15th century astrolabe on a Portuguese shipwreck off Oman provides a fascinating insight into an exciting period of the Age of Discovery.

Found within the wreckage of the Esmeralda, a carrack that sailed in Vasco da Gama‘s 1503 fleet to India, it is one of the most unique of more than 3,000 bronze artefacts so far found on the vessel since its discovery in 2015. Indeed it is reckoned to be the oldest such instrument found to date.

Laser scanners have revealed the etches on the astrolabe

Better known as an astronomer’s tool, the astrolabe was miniaturised and adapted for navigational purposes in the 15th century, at a time when mariners and explorers began plying their trades further and further from home. No longer safe to rely on their navigational experience and dead-reckoning, these pioneers began to turn to ‘scientific’ instrumentation to supplement their knowledge of the treacherous seas.

Early attempts at measuring the position of a ship away from the coast relied on the Pole Star, ‘the most easily observable heavenly body…The altitude of the Pole Star – its angle above the horizon – grew less as a ship sailed further south, and so gave an indication of how far south she had sailed’. (Parry, 1963, p.107)

Initially calculated by rough-eye estimates, these ‘measurements’ were enhanced during the 15th century by the popularisation of the mariner’s quadrant.

A mariner’s quadrant

The quadrant was soon superseded, amongst the Portuguese at least, by the astrolabe, which:

Consisted of a brass disk engraved with a stereographic projection of the heavens and a rotatable grill, by means of which the movements of the more conspicuous heavenly bodies could be followed. It was principally intended as a calculating device for the use of astronomers; but on its reverse side it was graduated in degrees round the perimeter and fitted with a rotating sight bar or alidade for observing altitudes…Only the reverse side of the instrument was useful – or indeed comprehensible – to seamen. (Parry, 1963, p.108)

That said, da Gama is recorded to have used a larger astrolable on his breakthrough voyage to India than the one found on board the Esmeralda. This was primarily for use on shore to determine his latitude. How much benefit he derived from the device is not wholly clear, its limitations in uncharted lands and inclement weather unlikely to have filled him with confidence.

It is not even clear how skilled a navigator da Gama was, for little is known of his life prior to setting off on that historic voyage around the Cape of Good Hope in 1497. There are snippets of information suggesting that he studied mathematics and navigation at an inland school in the 1480s, which may have enabled some familiarisation with instruments such as the quadrant and astrolable.

Yet one of the most enduring stories of da Gama’s voyage ironically centres on him dispensing with all of his navigational tools, when a mutiny broke out amongst his fearful crew. It is worth repeating the account in some detail, if only in the words of da Gama’s chronicler:

Crew: We have had enough. This is indeed a terrible and evil place as we were told.

Da Gama: No! We go on! We go to India.

As the crew threatened open rebellion, da Gama slipped away to his cabin, returning with a bundle of his charts and his navigational instruments.

Da Gama: What are these?

Crew: Your charts and instruments, Captain.

The Captain stepped forward and threw his possessions into the sea.

Da Gama: Now there is no returning! We go on with da Gama and with God!

That was the last of the dissension in the ranks.

Ordering his men to trust in God – not to mention in his own divine leadership – da Gama freed himself of the burden of science, his successful landfall near Calicut in 1498 testament to the holy honour bestowed upon him by his patron Dom Manuel I.

At least that’s how the chronicle portrays it, for such a foolhardy act would surely have been beyond even a man of da Gama’s fiery temperament.

Dom Manuel I of the House of Aviz

In addition to being able to read and compile maps and charts as a way of plotting their course, the late medieval mariners needed to adapt to the new tools of their trade and this required some schooling.

For many it was a case of learning on the job, the seaman’s apprenticeship an invaluable if brutal introduction into life on the open ocean. The Portuguese developed navigational schools in the 15th century, with Prince Henry the Navigator’s semi-mythical institution at Sagres both a practical training centre and a somewhat primitive think tank at the same time.

Vasco da Gama’s voyages to India encompassed all of this 15th century learning, not to mention the personal characteristics that mattered; an explorer possessed of a character befitting of his mission, a master whose ambition for the House of Aviz was unbounded, and the navigational tools that guided the way.

The discovery of the astrolabe points to a time when maritime culture was undergoing profound changes, enforcing a level of exactitude and professionalism previously unattainable. This in turn opened up the globe to the processes of mercantilism and imperialism, with the benefits and detriments these brought to so many far-flung peoples.

A fleet of the Carreira da India departs Lisbon in a 1593 engraving by Theodor de Bry

Beautiful and beguiling, the astrolabe has stood the test of time, a marker in the ocean upon which Portugal, that impoverished cousin of Spain, created the first global maritime empire.

Within a few years of its inception the Carreira da India was in full flow, exotic spices and magnificent beasts flowing back to Lisbon along with troves of gold and treasure. A template had been created for Western Europe to grow rich, to upend its backward and unenlightened reputation and propel its states towards a glory hitherto unseen.

The world was truly never the same again.

Source

Parry, J. H. The Age of Reconnaissance: Discovery, Exploration and Settlement, 1450-1650 (1963)

Advertisements

Western Sahara Dreams of Freedom: from the Halls of the AU to the Cape that Made History

The re-admittance of Morocco into the African Union (AU) has raised hopes that Western Sahara will soon be rewarded with its long-claimed independence.

Freed from Spanish colonial rule in 1975, this barren desert province was soon subsumed by the Moroccans. The authorities in Rabat and El-Aaiún (the largest settlement in Western Sahara) subsequently fought to undermine the legitimacy of the breakaway Saharan Arab Democratic Republic (SADR), established in Algerian exile by the Polisario Front.

Sahrawi soldiers parade in Algeria
Sahrawi soldiers parade in Algeria

The Polisario Front waged guerrilla warfare against the Moroccan Army throughout the 1980s, with thousands of Sahrawi people fleeing to ‘temporary’ camps in Algeria to escape further colonial rule.

Gradually worn down by the superior firepower of its unwanted overlords, the Polisario Front lost any momentum it had gained from the SADR’s admission into the Organisation of African Unity – the AU forerunner – in 1984, the development that caused Morocco’s break with its African colleagues. Whilst many Sahrawis remained in a pitiful exile, others returned to their homeland, their resistance crushed, assimilation beckoning.

Violence has remained sporadic and low key since a UN-brokered ceasefire in 1991 and few outsiders know of this bitter territorial dispute.

Morocco controls everything west of the red boundary line - most Western Saharan territory of note
Morocco controls everything west of the red boundary line – most Western Saharan territory of note

Perhaps equally significant, and even less well-known, is the role West Saharan geography has played in history. In addition to being a staging post for the Saharan trade of the Middle Ages, it boasts a particularly devilish headland that once stood as a formidable barrier to European exploration.

Cape Bojador (in Spanish) or Abu Khatar (‘father of danger’ in Arabic), a bulging headland host to ferocious tidal currents, for several decades halted the navigational exploits of Prince Henry the Navigator of Portugal and his willing sailors.

Restricted to tacking along the coastline in their precarious barinels, the Portuguese accomplished an extraordinary feat in mapping in detail the outline of North Africa. However, there was one landmark they could not overcome.

In 1433 Gil Eannes attempted to breach the gates of Cape Bojador. Commissioned by Prince Henry – that semi-legendary member of the royal house of Aviz – Eannes undertook his foolhardy mission in search of a great Christian king believed to live deep within the African interior. This king, Prester John they called him, would ally his forces with Henry to smash the burgeoning power of the North African Moors, who threatened Iberian dominance of the Mediterranean.

Prince Henry
Prince Henry

Eannes failed in his venture, returning to spread further rumours of the perils of Cape Bojador; the tides that constantly changed direction, the ferocious winds that whipped up the dust from the Saharan coast to blind the mariners, and the great sea monsters that nipped with ravenous intent at his ship’s bow.

Prince Henry – ‘a man little less than divine’ according to court chronicler Zurara – was not to be deterred, however. Ensconced in his Vila do Infante at Sagres, surrounded by the world’s greatest cartographers and shipwrights, he planned Portugal’s domination of the high seas.

It was at the Vila do Infante that the idea of the caravel – the single greatest invention in maritime history – was born. The design of her lateen sails allowed her to navigate against the wind, a precious development in Portugal’s assault on the West African coast.

With a precursor to this fine vessel Eannes set sail once more in 1434. With the protection of his Christian God and the unfaltering belief of his most Christian Prince, Eannes rounded Cape Bojador. Untouched by the sea monsters, he cruised through the tidal maelstrom to set Portugal on its path to empire. His only observations of terra firma beyond the Cape were the signs of camel tracks in the sand, yet Eannes had secured his place in history.

In half-a-century Diogo Cao had reached the Congo River; in a few more years Bartolomeu Dias had rounded the Cape of Good Hope; by 1498 Vasco Da Gama had touched down in India and Portugal’s acquisition of a maritime empire began in earnest.

It is an oft-told tale but one in which reference to Western Sahara and Cape Bojador is rare. Perhaps it is deemed insignificant or unimportant in the grand scheme of things? Perhaps Western Sahara is too? After all, despite international recognition, precious little pressure has been put on Morocco to relinquish its hold on this historic land.

The innocuous-looking Cape Bojador - a barrier to medieval exploration
The innocuous-looking Cape Bojador – a barrier to medieval exploration

Despite the cautious optimism surrounding this latest development, several AU countries (including Algeria and South Africa) had wanted Morocco’s readmission to be subject to their acceptance of Western Sahara’s independence. Their wishes went unheeded.

Progress, perhaps, but Morocco’s burgeoning economic ties with the rest of the African continent may better explain its eagerness to join the AU. Why relinquish your colonies when the military and moral pressure is so weak?

Standing at the headland that few outside the academic creed remember, one hopeful of the future but acknowledging of the past might muse:

At this point stands the barrier between two worlds

A guard between the old and the new

The formidable cape that represents the resilience of the West Saharan

Conquered but untamed, subordinated but unassimilated

In pursuit of greater things we must first recognise the wealth of our land

Of the history and spirit embodied by our geography

With Abu Khatar watching over us we can feel secure.