Thursday, 22 November 2012

Romans and electricity

Electricity, it's a child of the 19th-century, right? The Romans might have been pretty clever but they never mastered putting a D cell in a torch...or did they? There does seem to be at least some evidence of wet-cell batteries being used on the peripheries of the Roman Empire. The famous Baghdad Battery is more closely related to the post-Persian Parthian Empire, but these two ancient super powers shared borders, Greek culture and technology. Okay, so what was the Baghdad battery? Several five-inch tall clay jars have been found around Mesopotamia (modern day Iraq) containing hollow copper cylinders and iron rods that appear to function as anodes and cathodes when the jar is filled with acid. Voltages of up to 0.5-volts have been recorded from modern copies of these vessels using vinegar, and their performance could certainly be boosted if a stronger acid were to be used - the Romans and Parthians would have been quite capable of manufacturing sulphuric and hydrochloric acids which should be able to boost these wet-cells into the region of 4 or 5 volts. All right, so they had a battery...what was it used for? There's a couple of theories. During this period the Romans and the Egyptians were using bio-electric fish - such as the Torpedo Fish (the electric ray) - to numb severe pain; including gout, child birth and migraines. One could imagine an electric ray would be hard to find in the Mesopotamian deserts, so a 'clay ray' battery might have been a worthy alternative. Then there's the jewellers. Just as we dress up silver by electroplating it with gold, the ancients probably cottoned on pretty quickly to the same game. Importantly, both pain relief and fiddling the jewellery would have provided sufficient cash equity to experiment with battery technology if nothing else. But is that all? Well, maybe. These 'batteries' don't show up in Roman or Parthian rubbish dumps like an Eveready or Duracel would these days...but, maybe, just maybe, Thomas Edison wasn't the first guy to invent the light bulb...more on that later.

Find out if Calvus had a light bulb moment