Sigmund Freud, discussing the dissolution of military groups in “Group Psychology and the Analysis of the Ego” (1921), notes the panic that results from the loss of the leader: “The group vanishes in dust, like a Prince Rupert’s drop when its tail is broken off.”
That perhaps ,is a very apt analogy. Prince Rupert’s Drops are a paradoxical result of a glass tempering technique. They are created by dropping molten glass into very cold water as it cools, it creates a clear tadpole-like droplet that’s bulletproof on one end, but impossibly fragile on the other.
In fact, they were the precursor to bullet-proof glass.
The head portion of the drop is indestructible, to forces including hammer and bullet, and even an industrial pressure weight.
however the tail, when under the slightest pressure, makes the whole unit fragile and explosive as the energy flows to the head, the drop explodes very quickly .
The researchers said that this gives the droplet heads very high fracture strength, and to break the droplet, a crack that enters the interior tension zone of the drop must be created.
This tension is released when the tail is even slightly tweaked, and releases a cascade of energy that propagates the entirety of the tail and bulb, exploding it outward.
But since cracks tend to grow parallel to the surface, they can’t enter this tension zone.
So the easiest way to break a drop, is to break its tail, since disturbances in this area allow cracks to enter the tension zone because the drop is in a state of unstable equilibrium, which can easily be disturbed .
A compression force is one that squeezes material together, while a tensions force is one that pulls materials apart.
Scientists concluded that the surface of these drops experiences high compression stresses, while the inside experience high tension forces which makes the drops unique .
Scientists have known about these droplets for 400 years, but have only recently figured out what makes them almost indestructible.
The high fracture toughness is due to residual compression stresses making Prince Rupert’s drops one of the earliest examples of tempered glass.
Named after Prince Rupert of the Rhine, although he did not discover the drops, he played a role in their history by introducing them to Britain in 1660.
Prince Rupert of the Rhine
Rupert was born on 17 December 1619 in Prague , and known as a noted German soldier, admiral, scientist, and , colonial governor during the 17th century.
His full title was count palatine of the Rhine, duke of Bavaria but he was known as Prince Rupert of the Rhine.
His father, the elector palatine, was briefly ruler of Bohemia, but in 1620 was forced to flee to the Netherlands, where Rupert spent his childhood.
His mother was Charles I’s sister Elizabeth.
Rupert became a soldier and fought in the Thirty Years War (1618 – 1648). This gave him useful military experience when, in 1642, he joined Charles I’s army in the English Civil War, where he first came to prominence as a Cavalier commander.
Rupert’s father was a leading member of the Holy Roman Empire and the head of the Protestant Union, with a martial family tradition stretching back several centuries ,at the heart of a network of Protestant rulers across Northern Europe, Frederick ‘s close ties were also through his mother to the ruling House of Orange-Nassau in the United Provinces.
The family lived an extremely wealthy lifestyle in Heidelberg, enjoying the palace gardens—the Hortus Palatinus, designed by Inigo Jones —and a lavish castle with one of the best libraries in Europe.But when Frederick allied himself with rebellious Protestant Bohemian nobility in 1619, expecting support from the Protestant Union in his revolt against the Catholic Ferdinand II, the newly elected Holy Roman Emperor, support was not forthcoming.
As a result – crushing defeat by his Catholic enemies at the Battle of White Mountain in 1620.
Rupert’s parents were mockingly termed the “Winter King and Queen” as a consequence of their reigns in Bohemia having lasted only a single season.
After the restoration of the monarchy in 1660, Rupert held a series of British naval commands, fighting in the Second and Third Anglo-Dutch Wars. He died on 19 November 1682.
Exiled, Rupert was almost left behind in the court’s rush to escape , until a court member, tossed the prince into a carriage at the last moment.
Rupert accompanied his parents to The Hague, and spent his early years there and at the courts of his uncle King Charles I, before being captured and imprisoned during the middle stages of the Thirty Years’ War.
At 14 , Rupert attended the Dutch pas d’armes with the Protestant Frederick Henry, Prince of Orange and later fought alongside him, at the Anglo-German siege of Rheinberg.
By 1635 he was acting as a military lifeguard to Prince Frederick and fought against imperial Spain in 1637 in the Netherlands.
He was soon appointed to lead the royalist cavalry and fought in the first major battle of the war at Edgehill in October 1642.
His cavalry charge completely routed the parliamentarians but he got carried away and pursued them too far from the battlefield, losing the chance to inflict a decisive defeat.
Other military successes gave him a formidable reputation although his relationships with other Royalists commanders were poor.
They thought him arrogant and he was impatient with what he saw as their lack of professionalism, which ultimately resulted in his removal from post and ultimate retirement from the war.
During an invasion of Westphalia; Rupert escaped death, but was captured by the forces of the Imperial General Melchior von Hatzfeldt .
Towards the end of the battle, he made a failed attempt to bribe the army and was imprisoned.
The event was surrounded by religious overtones.
His mother was deeply concerned ,he might be converted from Calvinism to Catholicism.
Rupert’s captors, encouraged by Emperor Ferdinand III, deployed Jesuit priests in an attempt to convert him.
Then the Emperor went further, proffering the option of freedom, and a position as Imperial general with a small principality ,if Rupert would convert.
Rupert refused.
His release was ultimately negotiated through Leopold and the Empress Maria Anna; in exchange for a commitment never again to take up arms against the Emperor.
Rupert was later employed by the young King Louis XIV of France to fight the Spanish during the final years of the Thirty Years’ War, but Rupert’s military employment was complicated by his promises to the Holy Roman Emperor ,that had led to his release from captivity in 1642 – the same yr he became a Knight of the Garter in 1642.
In 1644, Rupert led the spectacular relief of the siege of York but then in July,
he was defeated by a parliamentary army at Marston Moor, losing York and the north of England for the royalists.
In June 1645, he took part in the Battle of Naseby at which the royalists were defeated.
Rupert now advised Charles to seek a treaty with parliament, but the king believed he could still win.
In September, Rupert surrendered Bristol to parliament.
In response the king abruptly withdrew his commission.
Rupert left for exile in Holland.
In 1648, a relatively brief Second English Civil War broke out, and Rupert informed the French King that he would be returning to King Charles I’s service, but part of the English navy mutinied and sailed for Holland where, in January 1649, the Prince of Wales gave Rupert command.
The naval campaign took Rupert’s ships to Kinsale.
Then he went to Lisbon and in November 1650 to defeat by Commonwealth Admiral Robert Blake ,off Carthagena in south east Spain.
Rupert escaped and spent the next decade in the West Indies and then in Germany.
The Parliamentary navy mutinied in favor of the King and sailed for Holland, providing the Royalists with a major fleet for the first time since the start of the civil conflict.
Rupert joined the fleet under the command of the Duke of York, who assumed the rank of Lord High Admiral.
Rupert argued that the fleet should be used to rescue the King, then being held prisoner on the Isle of Wight, while others advised sailing in support of the fighting in the north.
The fleet rapidly lost discipline, with many vessels’ crews , focusing on seizing local ships and cargoes.
This underlined a major problem for the Royalists—the cost of maintaining the new fleet that was well beyond their means.
Discipline continued to deteriorate, and Rupert had to intervene personally several times, including defusing one group of mutinous sailors by suddenly dangling the ringleader over the side of his vessel and threatening to drop him into the sea.
Most of the fleet finally switched sides once more, returning to England in late 1648.Following a degree of reconciliation with Charles, Rupert obtained command of the Royalist fleet himself.
His naval campaign formed two phases.
The first involved the Royalist fleet sailing from Ireland to Portugal.
He took three large ships, HMS Constant Reformation, the Convertine and the Swallow, accompanied by four smaller vessels.
Rupert sailed to Lisbon taking several prizes on route, where he received a warm welcome by King John IV, -ruler of recently independent Portugal.
In the second phase of the campaign, Rupert crossed back into the Atlantic and cut west to the Azores, capturing vessels as he went.
He intended to continue on to the West Indies, where there would be many rich targets, but he encountered a late summer storm, leading to the sinking of the with the loss of 333 lives—almost including Rupert’s brother, and a great deal of captured treasure.
Turning back to regroup, repair, and re-equip in early 1652, Rupert’s reduced force moored at Cape Blanc,
Rupert took the opportunity to explore.
At one point ,exploring 150 miles up the Gambia River, and taking two Spanish vessels as prizes, contracting malaria in the process.Rupert then finally made a successful crossing into the Caribbean, first at Saint Lucia, and then continuing up the Antilles to the Virgin Islands.
There the fleet was hit by a terrible hurricane, which scattered the ships and sank the Defiance, this time with his brother,Prince Maurice, on board.
It was a while before Maurice’s death became certain, and came as a terrible blow to Rupert.
He was forced to return to Europe, arriving in France in March 1653 with a fleet of five ships.
It soon became clear,the venture had not been as profitable as hoped.
In 1654, Rupert appears to have been involved in a plot to assassinate Oliver Cromwell, an event that would then have been followed by a coup, the landing of a small army in Sussex, and the restoration of Charles II.
Charles himself is understood to have rejected the assassination proposal, but three conspirators— who implicated Rupert in the plan—were arrested and confessed in London.
Rupert’s presence at the royal court continued to be problematic, he was regarded as an obstacle to peace negotiations; in 1655 Rupert left for Germany.
Very early on in the Society’s history, Rupert demonstrated Prince Rupert’s Drops to King Charles II and the Society.
Exhibiting the glass teardrops which explode when the tail is cracked; although credited with their invention at the time, later interpretations suggest that he was instead responsible only for the introduction of an existing European discovery into England.
The drops are reliably reported to have been made i in North Germany, at least as early as 1625.
However, its claimed that they were invented in the Netherlands (although it has been suggested that they had been known about by glass makers since the time of the RomanEmpire), hence common names for them in the 17th century were lacrymae Borussicae (Prussian tears) or lacrymae Batavicae (Dutch tears).
Rupert gave the reports gave to King Charles II, who in turn delivered them in 1661 to the Royal Society (which had been created the previous year) for scientific study.
Several early publications from the Royal Society give accounts of the drops and describe experiments performed.
His publication laid out correctly most of what can be said about Prince Rupert’s Drops without a fuller understanding than existed at the time, of elasticity and of the failure of brittle materials from the propagation of cracks.
They were studied as scientific curiosities by the Royal Society and the unraveling of the principles of their unusual properties probably led to the development process for the production of tempered glass, patented in 1874.
Rupert became involved in the development of mezzotint, a “negative”, or intaglio printmaking process which eventually superseded the older woodcut process and also developed a process for “painting colours on marble, which, when polished, became permanent
Rupert solved other military problems, and took to manufacturing gun locks; he devised both a gun that fired multiple rounds at high speed, and a “handgun with rotating barrels”.
He is credited with the invention of a form of gunpowder, which had a force of over ten times that of regular powder; a better method for using gunpowder in mining.
During this time, Rupert formulated a mathematical question Prince Rupert’s cube concerning the paradox that a cube can pass through a slightly smaller cube; Rupert questioned how large a cube had to be in order to fit. Rupert was also known for his success in breaking cypher codes.Many of Rupert’s inventions were military. After designing the Rupertinoe naval gun, he erected a water-mill on Hackney Marshes for a revolutionary method of boring guns, however his secret died with him, and the enterprise failed.
While focusing on naval inventions, he devised a balancing mechanism to allow improved quadrant measurements at sea, produced a diving engine for retrieving objects on the ocean floor.
Rupert’s health during this period was also worsening; his head wound from his employment in France required a painful trepanning treatment, his leg wound continued to hurt while he still suffered from the malaria he had caught while in the Gambia.
While recovering from his treatment Rupert set about inventing new surgical equipment to improve future operations.Some of Rupert’s scientific work lay in the field of metallurgy – inventing a new brass alloy, slightly darker in hue than regular brass, involving three parts of copper to one part of zinc, combined with charcoal.
This became known as “Prince’s metal” in his honour—sometimes also referred to as “Bristol Brass“. Rupert invented the alloy in order to improve naval artillery, but it also became used as a replacement for gold in decorations.
Rupert died at his house at Spring Gardens, Westminster, on 29 November 1682 after a bout of pleurisy, and was buried in the crypt of Westminster Abbey on 6 December in a state funeral