The costing clerks and accountants at Rowntrees used these in the ’60s, spinning them like magicians’ wands to mystify young marketing assistants. If you needed to know how any change to the KitKat packaging would affect earnings, you just had to watch the magic.
One thought on “THIS is a slide rule”
Janus, I was in infants and junior school in the sixties. Had I come across one of these cylindrical gadgets I would probably have tried to roll it along the floor like a steam roller, or simply used it to hit my older brother 🙂