The photo: "A Siemens machine generating gummed tape, 1934" shows 5-level tape, but with dual sprocket holes on the outside edges, rather than between holes 2 & 3. I've never seen that before.
The photo: "A Siemens machine generating gummed tape, 1934" shows 5-level tape, but with dual sprocket holes on the outside edges, rather than between holes 2 & 3. I've never seen that before.