More About 20th Century Wire Rim Frames...
Wire rim frames were introduced in the early 1880s.
Examples include: riding temple spectacles (1885-1915), Windsors (1885-1960s), Marshwoods (1921-1947), rimless frames with a saddle bridge (1885-1920), rimless frames with nose pads (1921-1950), semi-rimess or Cortlands (1921-1950).
Frames made after the 1950s are categorized by decade: 1960s, 1970s, 1980s, 1990s, and so on.
Of course, there is some overlap of style between decades.