Second, Third, Fourth: counting revolutions.

The Second Machine Age. The Third Industrial Revolution. The Fourth Industrial Revolution.

Robots – the second machine age (the MIT guys)

Third Industrial Revolution – computers and the Internet (Rifkin)

Fourth Industrial – Internet of things? (Schwab, maybe also Rifkin?)

Fifth?

Singularity – merging human and machine (Kurzweil?)

Posthuman, transhuman age?

Steam, Electricity (both energy), Cars (transport) and Digital (information).