I just love the concept of machines that run forever without looking after them. I know it's not a reality but it's still impressive how far we actually got. Cornelis Drebbel, who invented the submarine was granted a patent in 1598 for a machine that told the time, date, and season. The goldmachine was mounted in a globe on pillars and was powered by changes in air pressure a sealed glass tub with liquid varied in volume through atmospheric pressure changes. James Cox and John Joseph Merlin build the Cox's timepiece around 1760. The device is powered from changes in atmospheric pressure via a mercury barometer. The driving barometer contains 68 kilograms (150 pounds) of mercury. The clock is designed to enable the timepiece to run indefinitely and overwinding is prevented by a safety mechanism. The prime mover, encased in a finely detailed clock body, is a Fortin mercury barometer. Arthur Beverly build the Beverly Clock in 1864. The clock has been running continuously since its construction. The mechanism is driven by variations in atmospheric pressure and by daily temperature variations. Either cause the air in a one cubic-foot air-tight box to expand and contract, pushing on a diaphragm. A six-degree Celsius temperature variation over the course of each day creates enough pressure to raise a one-pound weight by one inch or 11 joules. Jaeger LeCoulter created the Atmos, a modern clock powered by the same principle as the Beverly Clock and Cox's clock. A mixture of gas and liquid (ethyl chloride) expands as the temperature rises and compresses a spring. For two days operation a temperature variation of one degree in the range between 15 and 30 degrees Celsius is enough. It also uses a torsion pendulum that executes two torsional oscillations per minute. In a mechanical watch the mainspring stores the energy to operate, a long strip of hardened and blued steel or some specialised steel alloy, iron-nickel-chromium with the addition of cobalt- molybdenum- beryllium and cold-rolled for hardening. Sich spring on average is about 0.05–0.2 mm thick. A torsion pendulum rotates about the vertical axis of the wire, spinning it, instead of swinging like a pendulum, it has a heavy disk or wheel with 3 or 4 chrome balls on ornate spokes, hanging on the torsion spring. The force of the twisting torsion spring reverses the direction of rotation, so the torsion pendulum oscillates slowly, clockwise and counterclockwise. The speed can be tuned by adjusting the spokes with the 4 balls that act like a governor. The clock's gears apply pulses at the top of the torsion spring to keep the wheel going as it rotates slowly it only takes little energy. the oscillation period changes with temperature. The closer the balls move to the axle, the smaller the moment of inertia and the faster it will turn.