Over the centuries the development of clocks and methods of measuring and displaying time have evolved from the use of shadows, sand, water, mechanical and electrical devices to electronic systems and atomic clocks. There have been particular developments that stand out, which are worthy of mention. The development of an accurate maritime clock two centuries ago was a great achievement of one man that improved the world of maritime navigation. The development of the Clock of the Long Now, also called the 10,000-year clock is funded with $42 million by Bezos Expeditions in the Sierra Diablo, a small mountain range in the US state of Texas. Development started on a prototype in 1987, which was running before the end of the last millennium and registered the time of the change of the millennium to the year 2000. The 150 metre high clock, designed to run for ten thousand years, is under construction inside a mountain.