1876
Energy
Germany
Four-stroke internal combustion engine
Nicolaus Otto's cycle made a compact, efficient engine.
Why it mattered
The powerplant of the automobile century.
Industrial Age
1876
2 recorded milestones at this point in the record.
1876
Communication
United States
Telephone
Bell patents the transmission of speech over wire.
Why it mattered
The human voice, not just code, could cross a continent.
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