Assertion: telescope's mirror | /r/HasProperty | ground by grubb
Facets:
value: in the 1950s
type: TEMPORAL
value: although until 1956
type: TEMPORAL
Source sentences:
text: The mirror was ground by Grubb in the 1950s, although until 1956, according to Observatories and Telescopes of Modern Times, there was some consideration to buying a new 74-inch from Grubb.