Archimedes’ greatest inventions and discoveries

That invention – the Archimedes Dial – may be fictitious (although it could be based on a real artefact, the Antikythera mechanism), but Archimedes himself left quite the legacy of discoveries. Here are six of the most significant…

Archimedes’ Principle

Appearing in Archimedes’ work On Floating Bodies, this foundational law of hydrostatics – the study of fluids at rest – states that an object placed in a fluid will have an upward buoyant force equal to the weight of the fluid that the object has displaced.

That’s the technical definition, but suffice to say that this revolutionised our understanding of how objects behave in water.

According to the apocryphal tale, Archimedes’ breakthrough with water displacement came after watching the water rise in his bath. He then celebrated with a naked run while yelling “Eureka!” (“I have found it!”)

What he had found was a way to complete the task set by the king of Syracuse: working out whether his new solid gold crown was actually solid gold, or mixed with silver.

By taking a lump of gold the same weight as the crown and lowering both in water, he could see if they displaced different amounts of water – and so had different densities.

Archimedes Screw

Gaining a better understanding of the behaviour of water was already an impressive feat for Archimedes, but with this invention he hoped to be able to control its movement.

The premise was simple: a hollow cylinder with a close-fitting screw running along its length, which would be turned by a treading mechanism. By placing the cylinder at an angle with one end in water, a person could transport water from a lower to higher level, in defiance of gravity.

While a rudimentary screw pump existed in Egypt before him, and another possibly kept the Hanging Gardens of Babylon watered, Archimedes is the name honoured on the screws still in use to this day.

The warship Syracusia

On the orders of King Hieron (Hiero) II of Syracuse, Archimedes designed a ship that dwarfed all others in the ancient world, the Syracusia.

With a 55-metre length and enough timber for 60 standard ships used by the Greeks at the time, it was reported to carry up to 1,800 tons of cargo and nearly 2,000 people, who could enjoy the library, gymnasium, dining room, gardens and temple on board.

The Syracusia was defended by towers manned by archers and a full-size catapult at the front of the deck. Not that it needed much protection: since it was too big for any of the harbours in Syracuse, the ship sailed only once to be gifted to the Egyptian pharaoh, where it disappeared from the historical record.

Archimedes' Odometer

The first-century-BC Roman architect and engineer Vitruvius credited Archimedes with the first odometer, a mechanical device to measure distance, developed during the First Punic War (264-241 BC).

Archimedes designed a cart and worked out how many revolutions of its wheels were needed to cover a mile.

A series of gears counted the wheel turns and, once it hit the mile mark, it set off another, larger gear that dropped a pebble into a box on the cart. If it existed, it would have been an engineering triumph: even Leonardo da Vinci could not recreate Archimedes’ odometer.

Archimedes’ Heat Ray (aka Death Ray)

Perhaps the Archimedes invention that requires the biggest leap of faith to believe it actually existed was his heat ray, sometimes referred to as the Death Ray.

It sounds like a contraption more suited to a James Bond villain, and acted accordingly: a set of mirrors would be set up and angled to focus the sun’s rays on a Roman ship, causing it to catch fire.

Historians continue to debate whether Archimedes’ heat ray was real, and engineers debate whether it would have worked even if it did exist.

Archimedes' Claw

During Archimedes’ defence of Syracuse from a Roman siege in the Second Punic War, the sinking of enemy ships was crucial.

One devastatingly effective weapon he developed was the claw, a crane that reached out from the city walls over the water with something akin to a grappling hook on the end.

This would be smashed down onto a Roman ship, where it took hold and lifted back up – bringing the hooked vessel with it.

Unlike some of his other war machines (like the heat ray) the claw has been shown to work, when the 2004 television show Superweapons of the Ancient World built and tested a replica.