While water clocks and, even earlier, sundials had been in use for centuries, it wasn’t until the end of the 13th century that weight-powered mechanical clocks began to appear. Who exactly invented the first mechanical clock is lost in time — excuse the pun — but records show that complex escapements and mechanical clocks were becoming commonplace in church towers by the close of the 14th century in Europe.
Since then, the accuracy of mechanical clocks has been consistently improved, doubling in accuracy about every 30 or so years on average.
Today there are many people around the world with some sort of eye deficiency, so it’s a good job we have eyeglasses to help correct vision. This wasn’t the case before the late-13th century, as prior to the invention of the spectacles in Italy the optical powers of lenses were poorly understood. Even after they were developed, only the richest visually impaired would have been able to afford a pair of specs to help them see.
After the Chinese had invented gunpowder they soon created something called ‘fire arrows’. These weapons were standard arrows with a tub of gunpowder strapped to the shaft that exploded on contact. By the early-13th century, fire arrows had evolved into rockets, with individual arrows carried at great speed by attached rocket tubes, very much like modern-day fireworks.
The windmill was invented in eastern Persia during the ninth century. According to surviving documents, these early windmills had between six and 12 sails made up from reed and cloth matting and were used to either grind grain or draw up water — the latter typically as part of an irrigation system. The now-traditional horizontal-axle windmill (pictured) — such as those found in Holland — was invented much later, appearing in Europe during the 18th century. Today, windmills have declined in use, though their principles still apply to newer inventions such as wind turbines.
Invented by Chinese alchemists, gunpowder is one of the deadliest-ever human creations. In its original form — a mix of potassium nitrate, charcoal and sulphur — it was used to power a fire lance, a primitive spear launcher made from a bamboo tube and reinforced with metal hoops. Through the Middle Ages its use became ever-more refined for shooting cannons and muskets.