Assertion: watt's steam engine | /r/HasProperty | dominant source of power
Facets:
value: until the early 20th century
type: TEMPORAL
Source sentences:
text: Reciprocating piston type steam engines were the dominant source of power until the early 20th century, when advances in the design of electric motors and internal combustion engines gradually resulted in the replacement of reciprocating (piston) steam engines in commercial usage.