Genaille's rulers (Genaille–Lucas rulers)
Reglas de Genaille (reglas de Genaille-Lucas)
- Date
- 1885-1891 · confidence medium
- Place
- France
- Credited to
- Henri Genaille (1891), from a problem posed by Édouard Lucas
- Field
- Knowledge & symbols
What it is
Arithmetic tool using graduated rods that represent carrying graphically, letting the user read off a multiplication result directly with no intermediate mental calculation; devised by railway engineer Henri Genaille from a problem posed by Édouard Lucas.
What it led to
- popularization of mechanical calculating aids in education
- division variants (Genaille–Lucas division rulers)
- a precedent in the history of mechanical calculators
- renewed didactic interest in modernized Napier's bones