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The quadrant was soon superseded, amongst the Portuguese at least, by the astrolabe, which: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

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Iran Plays Powerful with Control Over Hormuz Strait; 500 Years on from Afonso de Albuquerque

The Strait of Hormuz is one of the most strategically important waterways in the world today.  Providing the only sea passage between the Persian Gulf and the open ocean, it is used to transport approximately 20% of international petroleum requirements from the Middle Eastern oil fields.

The Strait of Hormuz has great strategic and, by extension, military importance
The Strait of Hormuz has great strategic and, by extension, military importance

At its narrowest, the Strait flows between Iran to the north and the Omanian exclave of Musandam to the south.  It has been the scene of diplomatic incidents, military clashes and maritime collisions but to Tehran, in particular, it is a chokepoint of great potential.

The Iranians periodically threaten to close the Strait of Hormuz and have, indeed, made the potential for such a scenario central to their belligerent foreign policy.  It is the United States, unsurprisingly, that is typically the target of such threats and whilst Iran would suffer from halting oil shipments out of the Persian Gulf, its control over the Strait is an undoubted bargaining tool.

It is 500 years since the great Portuguese explorer, conqueror and administrator Afonso de Albuquerque perished in Goa, that strategic gateway to India whose capture secured a foothold for Lisbon in Asia. Eight years prior to his death, Albuquerque had sailed into the Strait of Hormuz on the orders of his patron, King Manuel I of the House of Aviz.

Ever since Vasco da Gama had landed at Calicut in 1498, the Portuguese had been in competition for dominance over the lucrative Indian Ocean trade with Muslim merchants, whose own commercial routes stretched all the way to Egypt and the Mamluk Sultanate, Manuel’s rival in the Mediterranean.  Capturing Ormuz Island on what is today Iran’s southern coast would be a major step in thwarting Muslim ambitions.

Da Gama's famed voyage initiated an era of worldwide European exploration and conquest
Da Gama’s famed voyage initiated an era of worldwide European exploration and conquest

With little effort, Albuquerque and his men captured their target in October 1507, only for their joy to be short-lived.  In a harsh climate without sufficient supplies, Albuquerque’s aim to build a garrison to hold the island led to resentment amongst his subordinate captains and provoked resistance from the local population.  A mutiny of the Portuguese ensued, whereby all bar Albuquerque’s ship returned to Portuguese India and Ormuz was lost.

Not to be deterred – and after securing Goa and Malacca in a series of brilliantly daring raids – Albuquerque returned to Ormuz again in 1515 with more than 1,000 men in 27 heavily-armed vessels.  This time the conquest led to the establishment of a permanent garrison, effectively cutting off the Indian Ocean to the Muslim merchants and securing the first overseas empire by a European power.  Indeed, it would not be until 1622 that the Portuguese presence at Ormuz was ended by the British.

Ormuz offered the Portuguese a grasp on both the Indian and Persian trade
Ormuz offered the Portuguese a grasp on both the Indian and Persian trade

There are few men as ‘great’ as Albuquerque today – and this term refers to his military and administrative achievements not his propensity to dispense brutal justice to those who dared cross him – nor as pioneering as his predecessors da Gama and Francisco da Almeida.  Indeed, we live in a world where such personalities are discouraged and any sense of individualism is often treated with noted scepticism.

Albuquerque was a formidable character...so much so that he earned the sobriquet O Terrível (The Terrible)
Albuquerque was a formidable character…so much so that he earned the sobriquet O Terrível (The Terrible)

The 16th century was characterised by the disproportionate achievements of the few against the many.  Nowadays it often appears as if thousands upon thousands of faceless diplomats and bureaucrats are incapable of creating the slightest change.  The Iran nuclear deal took the involvement of hundreds of such characters and, whilst driven by a select few global ‘leaders’, time is likely to prove how ineffective this venture has been.

Iran’s threats ring hollow; closing the Strait of Hormuz would hurt its enemies but also itself.  Sometimes it is hard not to pine after the dashing era of Albuquerque and his bloody-minded cohorts, who could ride roughshod over the barricades and penetrate the enemy heartland, safe in the knowledge that their technological and martial superiority would grant them passage.

Alas; timid diplomacy, bureaucratic gridlock and unadventurous leaders are all we can hope for in our tormented world of scrutiny, cynicism and obstinacy.

Source

Crowley, R (2015), Conquerors: How Portugal Seized the Indian Ocean and Forged the First Global Empire