Hydraulics is an engineering subset that has been around for centuries. Early automaton used water pressure and flow to effect movement, and the industrial revolution in England may never have happened without using water power to drive machinery – water mills were used to make flour and also to provide energy to early machinery. Steam was also a popular technology, and although this could be classed technically as pneumatic, it grew from the lessons learned from using water power. Nowadays electrical alternatives are widely available and if hydraulics were invented now, this style of power supply would not be as popular as it is. Despite the age of the technology and the rise of electronic alternatives, hydraulic power still reigns in a few areas where there is no viable alternative. Underwater operations, potentially explosive environments and places where there is no electricity (or it cannot be used for environmental reasons) are three of the main applications where hydraulics is the go-to technology. The sturdy construction of hydraulic systems, designed to withstand huge amounts of internal pressure, can also withstand pressure from the outside as well. This means that underwater deep-sea operations, such as drilling and scientific research, make use of hydraulic technology that is reliable and fully functional even under the immense pressures of the deep ocean. Potentially explosive environments, such as those found in oil and gas plants or industries that use dangerous gases and chemicals, are not suited at all to electrical systems. The explosion risk from just one spark from an electrical system failure is great, so hydraulic systems are used to effect motion rather than those which rely on electrical input. Because it is possible to transfer energy over large distances using hydraulics, any electrical components can be housed far away from the explosive atmosphere. Lastly, in areas where there is no electrical supply, like the polar regions and other remote places, there is no way of using electrical power as a solution or even as an input power for a system. Hydraulic systems can be used with human power by way of a hand pump, converting human power into a larger force using the principles of hydraulics. This means that machinery that might otherwise be unsuitable for use in these places, can be powered by people and this increases the rate of productivity and development in isolated communities.