Assertion: sonar | /r/MadeOf | an array of nickel tubes
Facets:
value: typically
type: DEGREE
value: in 1940
type: TEMPORAL
Source sentences:
text: In 1940, US sonars typically consisted of a magnetostrictive transducer and an array of nickel tubes connected to a 1-foot-diameter steel plate attached back-to-back to a Rochelle salt crystal in a spherical housing.