Agfa and Ansco
12 and 9 researched events on one shared scale. Agfa 1867–present, Ansco 1840–1967.
The axis stretches where either maker has research and collapses where neither does, so a year sits opposite the same year on both. Event counts differ because research depth differs, not because one company did less.
Agfa1867–present · 12 events · 2 concurrent threads
Ansco1840–1967 · 9 events · 2 concurrent threads
1 span collapsed, 15 years in total, where neither maker has a research point: 1984–1998. Collapsing keeps a short-lived maker readable beside a long-lived one; the years are removed from the drawing, never from the record.