What kind of machine is the steam engine invented by Englishman Watt?

Before Watt, the steam engine in newcomen consumed a lot of coal and was inefficient.

From 1765 to 1790, Watt made a series of inventions, such as separate condenser, cylinder external insulation layer, piston lubricated with oil, planetary gear, parallel linkage mechanism, centrifugal governor, throttle valve, pressure gauge and so on. , make the efficiency of the steam engine to more than three times that of the original newcomen machine, and finally invented the modern steam engine.