Part 10/14:
Crawford draws an important contrast between two pivotal periods: 1870–1920 and the last 50 years.
In the earlier period, five revolutionary breakthroughs transformed multiple sectors simultaneously:
Electricity (generators, motors, lighting),
Internal combustion engines (cars, airplanes),
Communication technology (telephone, radio),
Synthetic chemistry (plastics, fertilizers),
Public health improvements (germ theory, sanitation).