Coral Castle & the Perpetual Motion Holder

The Coral Castle is a megalithic stone structure created by the Latvian American eccentric Edward Leedskalnin in Florida. The structure consists of several stones (mostly limestone) weighing an average of 14 tons. Mystery surrounds its construction as its considered to have been built single-handedly by Leedskalnin using magnetism and/or supernatural powers. Nowadays it serves as a tourist attraction.

Edward refused to let anyone observe him while working, though a few teenagers claimed to have witnessed his work, reporting that he had caused the blocks of coral to move like hydrogen balloons. The only tool that Leedskalnin himself spoke of using was a "perpetual motion holder."

Leedskalnin originally built the structure in Florida City around 1923, but decided to take it with him when he moved. It took him three years moving the structure the distance of ten miles to Homestead. He continued work on the Castle until he died in 1951.

Many of the features and carvings of the castle are notable. Among them are a two-story castle tower that served as Leedskalnin's living quarters, walls consisting entirely of 8-foot high pieces of stone, an accurate sundial, a Polaris telescope, an obelisk, a barbecue, a water well, a fountain, celestial stars and planets, and numerous pieces of furniture. The furniture pieces included are a heart-shaped table, a table in the shape of Florida, twenty-five rocking chairs, chairs resembling crescent moons, a bathtub, beds and a royal throne.

Baghdad Battery

The Baghdad Battery, also known as the Parthian Battery, is the common name of Mesopotamian artifacts discovered in 1936 near Baghdad (hence the name.) They were probably created in the Parthian or Sassanid period, between 250 BCE and 640 CE. In 1940, Wilhelm König published a paper speculating that they may have been galvanic cells, batteries, perhaps used for electroplating gold onto silver objects. This interpretation continues to be considered as at least a hypothetical possibility. If correct, the artifacts would predate Alessandro Volta's 1800 invention of the electrochemical cell by more than a millennium!

The pots contain an electrochemical couple of copper and iron, and so if one were to place a suitable acid, such as lemon juice, grape juice or vinegar, an electrical current would form. The voltage, however, would be very low with this particular pair of metals.

Antikythera Mechanism

The Antikythera Mechanism is an ancient mechanical computer built by the Greeks to calculate positions of astronomical objects. It is the world's oldest known analog computer. Recovered in the beginning of the 20th century from the Antikythera wreck, its significance was not completely understood until decades later. It is phenomenally accurate in its calculations of the positions of the moon and planets. Estimated to have been built sometime between 100 and 150 BCE, the technology was lost with the Ancient Greeks.

Similar works didn't start to reappear until the 14th century, which makes the Antikythera mechanism outdate them by over thirteen centuries!
The complexity of the device itself is more similar to the creations of 19th century Europe.

The device is displayed at the National Archaeological Museum of Athens and even has a project researching it, aptly named The Antikythera Mechanism Research Project.

Huolongjing

While the Chinese are widely known as the inventors of gunpowder, there are some surprisingly early innovations that are more obscure. These are catalogued in the early Ming dynasty book Huolongjing (Fire Dragon Manual in English) written in the 14th century.

The book showcases various gunpowder-powered devices ranging from flamethrowers to grenades to mines, both land and naval. It even has an explanation of the evolution of the 10th century exploding fire-arrow into a winged rocket. It also includes descriptions of various proto-firearms such as the fire lance, which fires flaming shrapnel like some sort of firey shotgun. There's also cannons complete with exploding cannonballs.

Although the western world surpassed the Chinese in terms of gunpowder technology in the 15th century, Huolongjing shows us what had been done with it for centuries before westerners ever laid eyes upon the destructive powder.

Tesla's Oscillator

Tesla's Oscillator also known as the Earthquake Machine, was invented in 1898 by Nikola Tesla, the genius innovator of electrical engineering. This small device (178 mm long) could cause metal objects to vibrate violently, even to the point of cracking a steel bar or crashing down a whole structure, such as the steel frame of a bridge. Tesla is said to have attached the device to the frame of his laboratory in New York and forgotten it there, causing an earthquake that spanned several buildings. As the vibrations grew stronger, Tesla was forced to smash the device with a sledgehammer.

Tesla later boasted that he could build a device that would cause a resonance in the Earth's core strong enough to crack the surface. Nobody demanded him to prove this claim.