Imagine if reaching your 40s came with a silent unavoidable tax that could end your career? For centuries, the natural hardening of the lens in the human eye did exactly that, forcing master craftsmen and scholars into unwanted early retirement.

A nameless 13th-century Italian began a revolution by creating the clearest lenses to correct this problem, but why did this rare luxury take centuries longer to become a mass-market necessity?

In this episode, we unpack the history of the spectacles, from state secrets protected by assassins, to the explosion of demand brought on by populist gossip and the work of Johannes Kepler, who mapped not only the planets but the properties of lenses, despite his own severe vision impairment.

Also, discover the bizarre engineering link between fish eyes and cameras, and a simple solution you can use if you forget your glasses.

Join Richard and Geoff to uncover the story of the ultimate "invisible tech".

Connect with us! Explore more deep dives into the epic engineering behind the invisible stuff you take for granted every day:

• Website: commonknowledgeclub.com

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Ever look at the beer bottles in your fridge or the bottle of wine on the counter and realize you’re staring at an engineering masterpiece? How did the twist-top save kitchen benches worldwide and frustration on camping trips? And how did the wine screw-cap cause a 'mutiny' in Australian wine makers?

Join us in this episode as we 'crack open' the history of these inventions. From the strange solutions that proceeded bottle tops to the subtle engineering that keeps win breathing. And the inventor with a surprising patent to his name.

Why did these inventions emerge? And what engineering is required for there success? All these will be discussed around the friendly fireside that is the Common Knowledge Club.

Connect with us! Explore more deep dives into the epic engineering behind the invisible stuff you take for granted every day:

• Website: commonknowledgeclub.com

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Go to your kitchen and look in the back of your pantry. Sitting in the dark is an object so profoundly boring, you probably haven't thought about it since the day you bought it: the tin can. But don’t be fooled! That little metal cylinder began life as a piece of pivotal military hardware.

In this episode, we uncover the intriguing history of the humble tin can. Discover how a desperate Napoleon Bonaparte funded the invention of food preservation, how iron-clad rations cemented the British Royal Navy’s dominance over the oceans and a fateful arctic journey that would change the canning technology forever.

But the wildest part? We produced this indestructible storage technology for a full fifty years before anyone actually invented a tool to open it!

You will never look at a can of soup the same way again.

Connect with us!Explore more deep dives into the epic engineering behind the invisible stuff you take for granted every day:

• Website: commonknowledgeclub.com

• Substack: commonknowledgeclub.substack.com

• Instagram: @thecommonknowledgeclub