250 BC – 240 BCs

Events in 250 BC – 240 BC 7

• 285 BC – 246 BC Library of Alexandria -- all human knowledge The Library of Alexandria, developed under Ptolemy II Philadelphus (285-246 BC), holds between 400,000 and 700,000 scrolls. Its scholars produce the first critical editions of Homer, develop geometry (Euclid), measure the Earth's circumference (Eratosthenes), catalogue the stars (Hipparchus) and lay the foundations of ancient science. It is the greatest intellectual institution of the ancient world.
• 264 BC – 241 BC First Punic War Rome's first conflict with Carthage — the great maritime empire of North Africa — begins over Sicily in 264 BC. Rome, a land power with no naval tradition, builds a fleet from scratch, reportedly copying a captured Carthaginian warship. The Romans add the "corvus" — a boarding bridge — to turn sea battles into land fights. After 23 years and enormous losses on both sides, Rome wins Sicily (241 BC), its first overseas province.
• 250 BC Archimedes invents the Archimedes screw A helical pump to raise water — still in use today King Hiero II commissioned Archimedes to design the Syracusia, the largest ship in classical antiquity. One problem was pumping bilge water from the enormous hull. Archimedes's solution was the screw pump: a helix inside a hollow cylinder, turned by a handle, which lifts water from a lower to a higher level. The device was so effective that it spread throughout the ancient world for irrigation and drainage. It is still manufactured and used today in water treatment plants and agricultural irrigation across the developing world.
• 250 BC On the Equilibrium of Planes — law of the lever "Give me a place to stand and I will move the Earth" In his treatise On the Equilibrium of Planes, Archimedes proved the law of the lever mathematically: that weights balance when they are inversely proportional to their distances from the fulcrum. He also identified the concept of the centre of gravity — the single point at which an object's entire weight can be considered to act. To demonstrate the lever's power to King Hiero, he single-handedly hauled a fully loaded merchant ship along the dock using a compound system of pulleys. His famous boast — "Give me a place to stand and I will move the Earth" — captures the principle perfectly.
• 247 BC – 224 Parthian Empire Persian revival; rival of Rome The Parthian (Arsacid) Empire restored native Iranian rule and became Rome's great rival in the east for nearly five centuries, its famed horse-archers and cataphracts repeatedly checking Roman expansion — most notably annihilating Crassus's legions at Carrhae in 53 BC.
• 246 BC – 208 BC Construction of the Great Wall begins Linking earlier walls into a unified northern defence Qin Shi Huang ordered the linking and extension of existing northern walls into a continuous defensive barrier against Xiongnu nomads. Hundreds of thousands of workers — soldiers, peasants and convicts — built the wall under brutal conditions. This early wall was largely of earth and wood; the iconic stone wall seen today was built by the Ming dynasty. The wall represents the most ambitious construction project of the ancient world.
• 245 BC Eureka! — Archimedes discovers buoyancy On Floating Bodies: a submerged body displaces its weight in fluid King Hiero II suspected a goldsmith had mixed silver into a supposedly pure gold crown. He tasked Archimedes to test it without destroying it. The solution came to Archimedes while stepping into a public bath — he noticed the water level rose as he entered, and realised that a body displaces a volume of fluid equal to its own volume. Since gold is denser than silver, a silver-adulterated crown would displace more water than a pure gold crown of the same weight. Legend says he leapt from the bath and ran naked through the streets shouting "Eureka!" (I have found it!). He formalised the principle in his treatise On Floating Bodies, the first systematic work in hydrostatics.