Humans have been using tools for at least 2 million years, and simple machines for an unknown period of time, but probably for at least 100,000 years.
The three basic needs for the development from scratch of a precision technology are a straight edge, a screw of uniform pitch, and a precise right angle.
An early rule known to many builders and engineers: to make a perfect right angle, draw a triangle with sides of 3, 4 and 5 units, or 5, 12 and 13 units.
An excellent level surface can be obtained over any distance with a sufficiently long trough or a water-proof trench filled with water that is not running.
Simple machines make work easier: levers, ramps, wheels and bearings, pulley systems, gears, drive belts all allow small efforts to shift large loads slowly.
Most simple machines are limited by the effects of friction. No machine can output more energy than is put into it, so perpetual motion is impossible.
The impossibility of perpetual motion does not stop charlatans trying to sell them to the unwary, the gullible and the greedy, and all too often, succeeding.
Looking at how they operate, levers can be placed in three classes, depending on whether the Fulcrum, Load or Effort is in the middle: the FLE orders of levers.
A first order lever, with the fulcrum located in the middle, is what you encounter when you use a pair of scissors or a pair of pliers to work with something.
A second order lever with the load located in the middle, is what you see when you use a pair of nutcrackers or a wheelbarrow, or row a boat (think about it!).
A third order lever with the effort located in the middle is what you see when you use a pair of tweezers or tongs with a spring at one end, or a fishing rod.
You can measure the velocity ratio and the mechanical advantage of any simple machine. Any observed differences are generally attributable to frictional effects
Hydraulic systems can act in place of many simple machines, in the sense, for example, that the hydraulic press acts as a lever, but can also change direction.
The wheel and axle, the screw and the wedge are all specialized forms of the same basic plan, the lever, when they are considered in the right way.
From another viewpoint, the screw and the wedge may be seen as special cases of the inclined plane, again when they are considered the right way.
In the first century AD, Hero of Alexandria made a variety of machines, including an aeolipile, a primitive toy steam turbine, rather like a garden sprinkler.
This file is http://members.ozemail.com.au/~macinnis/scifun/splatmachine.htm, first created on February 16, 2008. Last recorded revision (well I get lazy and forget sometimes!) was on February 16, 2008.