Tech that stands the test of time (pictures)

The author of the Oxford Electric Bell, or Clarendon Dry Pile, is unknown. Even its exact date is unknown. It was purchased by Oxford professor of physics from 1839-1965 Robert Walker, who labelled it "set up in 1840," but there is evidence to suggest that the experiment was set up 15 years earlier.

Whenever it was set up, whether 176 years ago or 191 years ago, it has been "ringing" continuously ever since. The pendulum clapper between two bells is powered by two "dry pile" batteries, sealed by a coating of molten sulfur. What's inside those sulfur columns is unknown, since no one wants to disrupt the experiment to find out. Popular opinion is that they contain Zamboni piles, invented by Giuseppe Zamboni in 1812 and consisting of discs of silver foil, zinc foil and paper. This creates a small electrostatic charge in the bell, which repels the clapper, so that it vibrates between the two bells as they continuously repel it back and forth.

The bells itself are inaudible now, but the experiment, on display on the ground floor of Oxford University's Clarendon Laboratory, can still be seen ringing away to this day. You can watch a video of it in action here.

An incandescent light bulb burns in a fire station in Livermore, California. As the world increasingly turns to LED lighting, this bulb has been burning almost continuously since being switched on in 1901. In 2001, it was named the Centennial Bulb because it had been burning for a century. The bulb itself, invented by Adolphe Alexandre Chaillet and made by the Shelby Electric Company, consists of a handblown glass bulb and carbon filament, and has only been turned off a handful of times in the 115 years since its installation. It currently burns at just four watts. You can watch a documentary on the Centennial Bulb here.

Set up in 1927 by Thomas Parnel at the University of Queensland, the Pitch Drop Experiment is one of the world's longest-running experiments. The aim is to measure the flow of pitch, which looks like a solid but is actually an extremely viscous liquid. The pitch used in the experiment has a viscosity 230 billion times that of water, only nine drops have formed and fallen since the experiment's inception.

Each drop takes a varying amount of time to form and fall into the beaker below, but the shortest amount of time was 7.2 years. Technically, the ninth drop didn't actually fall, either. The experiment's custodian changed the beaker in 2014, and the ninth drop, which was already in contact with the other fallen drops, snapped off.

The eighth drop fell in 2000, long before cameras had been set up to record a pitch drop falling. The first time a drop of pitch was filmed falling was in 2013, with cameras observing a different experiment set up at Trinity College Dublin. However, no one has ever witnessed a pitch drop falling, live with their own eyes.

The next drop is due to fall in around 14 years or so at current viscosity rates. If you want to tune into the live feed watch it yourself, you can do so here.

The Beverly Clock, currently housed at the Otago University's Department of Physics in New Zealand, hasn't been wound since its construction in 1864. Its mechanism was designed by Arthur Beverly, and it uses atmospheric changes to power the clock without any human input. As temperature changes, it operates a diaphragm that expands and contracts and powers the clock.

In the interest of fairness, the Beverly Clock has stopped before, when there weren't sufficient atmospheric changes to power the clock, or in the event of mechanical failure, but it has always started again.

Even more amazingly, this is not the first such mechanism. The first known clock to have been powered by atmospheric changes was built by Dutch inventor Cornelis Drebbel, who is also credited with building the first navigable submarine. He patented his atmospheric clock in 1598, and went on to build several in the 17th century.

There are several contenders for the crown of oldest working clock, including the movement of the Salisbury Cathedral Clock dating back to 1386 in the UK and the clock of St Andrew's in Chioggia, Italy from the same year, but the Beauvais Cathedral Clock in France is claimed to date back to 1305. It is not exactly the same clock. Since its installation, it has undergone repairs and restoration, but its carillon still chimes perfectly over 700 years later.

The Harwell Dekatron Computer, first switched on in 1951, has had a storied history that includes decommissioning and storage, but, having been extensively restored, it is now recognised as the world's oldest working digital computer. Its original purpose was performing calculations at the Atomic Energy Research Establishment in Harwell, Oxfordshire in the UK, with the ability to store up to 90 numbers in its dekatron-based memory.

After it was no longer needed at the research facility, the 2.5-ton machine was moved to the Wolverhampton and Staffordshire Technical College, where it was used to teach computing under its new name, Wolverhampton Instrument for Teaching Computing from Harwell, or WITCH. It was decommissioned in 1973, and remained in storage until 2009, when its recovery and restoration commenced under the supervision of the The National Museum of Computing at Bletchley Park.

The television was invented in the 1920s, but it wasn't sold as a home entertainment device until the 1930s. One of the very first models was the Marconi 702, which only showed picture, no sound. The CRT was set into the top of the cabinet, and a mirror lid displayed the image to the viewer.

This particular Marconi type 702 was sold on November 26, 1936, just three weeks after the BBC began transmitting the world's first high-definition television service, and is thought to be the world's oldest working TV set. It was sold at auction by Bonham's in 2011 for £16,800.

The auction page reads, "This screen would have shown the very first scheduled television programme in the world. The CRT picture quality is superb, with the ion-burn limited to very small spot. Presented here is the 702 proven to have been sold three weeks after the first transmission date in late 1936 -- an extraordinary discovery, complete with all supporting documentation."

It first hit the road in 1884, and the La Marquise is still running, making it the world's oldest working car. The legend goes that the young Comte de Dion was mesmerised by a toy steam engine spotted in a Paris toy store, and commissioned its creators, Georges Bouton and Charles-Armand Trepardoux, to build him a person-sized one.

The car itself uses a purpose-designed vertical boiler, using coal to produce the steam required to run the car's engine. It participated in and won the world's first automobile race in 1887 (it was the only car to make an appearance), and can travel 20 miles (32 km) at a speed of up to 38mph (61kph) on a full tank of water.

In 2011, it sold at auction for $4,620,000.