Dutch Tears, Explosive Failure Fronts, and Prince Ruperts Drops

300px-Prince_Ruperts_dropsA recent conversation about stress, how it seems to permeate this ever tightening society like an over-wound pocket watch spring, reminded me of something I had researched in one of my physics courses.

An almost magical glass structure called Prince Rupert’s Drops, Although they have been called many things over the centuries.. Dutch Tears, Rupert’s Balls, Verona Drops… their strange properties could never be explained. They’ve been around for a very long time, first discovered in Holland and later kept as a secret at the glass artisans at Mecklenburg, Germany. How about some poetry from 1663 mentioning this curiosity?

“And that which makes their Fame ring louder,With much adoe they shew’d the KingTo make glasse Buttons turn to powder,If off the[m] their tayles you doe but wring.How this was donne by soe small ForceDid cost the Colledg a Month’s discourse.

Ballad of Gresham College 1663


their tayles you doe but wring...”? Almost thou’est don’t sound english do’ith?

Anyway.. simple to make,  just drop some molten glass into a container of cold water and they will form their characteristic “tadpole” shape of glass.

make-prince-ruperts-drops-glass-fractures-speed-high-explosives.w654 So now you are probably thinking… “So what? They’re shaped like Tadpoles. What’s the big deal?”

This is where it getS strange and they have only recently been able to explain it. Take that glass tadpole and a hammer. Strike the head of the glass tadpole with the hammer. Go ahead… it’s not going to break or crack. STRIKE IT HARDER. Still there. Amazing strength.

BUT… crack or even scratch… the tail of the tadpole at the opposite end of the head. Suddenly the whole thing explodes into glass dust. A stress failure front develops and travels at a estimated speed of 6400 miles per hour, turning the glass to powder as it goes. Internal stresses locked in by the fast cooling effect of the water against the surface tensions. Mechanical chaos frozen in time really.



So what is going on? Seems the object, while the head part is almost completely invincible, is only as strong as its fragile tail when it releases all that “frozen” internal stress.


Thanks to the power of digital video cameras that can record at hundreds of thousands of frames per second, you can see just what happens when the tail is “bitten”

So getting back to the first sentence, talking about the stresses in American life today.. how the rich are getting richer and the poor are scrambling just to survive… reminds me of a quote. You may have heard it before.

“A nation’s greatness is measured by how it treats its weakest members.” ~ Mahatma Ghandi




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  1. That would seem a perfect metaphor: how’s yer old ass hanging? LOL Fascinating. Failure fronts… people rising up against the top? I just keep getting all of these metaphors…. Good stuff.

    • Krell says:

      Yes…. the metaphor of how the weakest are treated eventually comes back to even the hardest and strongest of the unit. Keep the direction we are going and we may be in for some “explosive” results, indeed.

  2. Ryan says:

    I know this isn’t going to make me the popular poster of the day, but I’m going to have to disagree with Mahatma Ghandi’s comment.

    Imagine two small nation states, Relaxandia and Investorville. The citizens of Relaxandia and extremely wealthy today, because they inherited extremely productive infrastructure from their grandparents generation. Relaxandia has the highest living standards in the world. Not one person in Relaxandia lives in poverty, because every citizen in the country is given up to $2500 worth of RelaxoBucks per month if they just ask for it.

    Meanwhile, Investorville is a relatively poor country. It spent the last two centuries at war with itself and invaded by foreign powers. Only in the last few decades has Investorville been getting it’s act together. There’s not much to go around, meaning that if someone doesn’t contribute, it’s up to their family to take care of them. If their family doesn’t have the resources or is unwilling to care, then the person who can’t contribute will probably not survive long.

    In the short term, life in Relaxandia is great. The rich are wealthy. Even the poor are relatively wealthy. It’s a very good life.

    Keynes is correct in his statement that “In the long run, we’re all dead”. The problem with this philosophy is that short term strategy NECESSARILY will loose when competing against a strategy. For Keynes, his logic works, because Keynes never had any children.

    Each day that Relaxandia and Investorville trade with each other, wealth will be transferred from Relaxandia to Investorville. Whether in your generation, your children’s, grand childrens or great-grand childrens, Investorville WILL be far wealthier than Relaxandia.

    When there are not enough resources to go around, there will be conflict.
    When there are plenty of resources to go around, there will be relative peace.
    A quick trip to some of the wealthy countries and poor countries will show this to be true.

    I think that Ghandi’s point misses the mark entirely.
    I think a nation’s greatness is measured by the strength and size and real incomes of the MIDDLE CLASS over the LONG TERM. That means that it should be easy for Rich people to fall into the middle class or under class if they make bad financial decisions. It should be easy for smart, motivated members of the under class to move to the middle class. Becoming “Rich” should be earned by those that contribute something valuable to the country and the citizens, not by those that work the system or inherit dynastic wealth.

    Want to know how to raise the incomes of the middle class? It’s easy.
    1) invest, invest, invest. total capital invested = wealth
    2) protect your nations businesses from foreign competition
    3) protect your citizens from jobs from foreigners, but not from domestic automation
    (better a job done with my robot than their robot, better done with our citizen than their citizen)

    The USA used to know how to do this. Alexander Hamilton was an expert at it. He called the key domestic firms “Infant Industries”. We called the entire quasi-mercantalist “rigged in our favor” trading system that made us rich the “American System”.

    Then we forgot how we got here, and now it’s too late to fix seventy years of the Military Keynesianism that followed the American System.

    • Krell says:

      Interesting comment. It has absolutely nothing to do with the post, but I decided to let the comment stand on its own. Your position would take on more significance if it had some subject continuity. Perhaps there was some other post that you were reading and placed this erroneously?

      • Ryan says:

        > It has absolutely nothing to do with the post

        The article starts with this comment:

        “A recent conversation about stress, how it seems to permeate this ever tightening society like an over-wound pocket watch spring, reminded me of something I had researched in one of my physics courses.”

        And ends with this quote from Ghandi:
        “A nation’s greatness is measured by how it treats its weakest members.” ~ Mahatma Ghandi

        Ghandi’s quote sounds nice, but like Keynes short term thinking, it does nothing for your grandchildren.

        There are lots of things we could do right now to reduce the FEELING of stress and poverty in the US. These actions would make people happier and reduce their stress levels TEMPORARILY, but the PROBLEM is that the citizens were not paying attention as the american industrial base was sold to East Asia.