Nomogram
Nomograms were widely used for about 75 years. They allowed quick and accurate computations before the age of pocket calculators. Results from a nomogram are got quickly and reliably by drawing one or more lines. The user does not have to know how to solve algebraic equations, look up data in tables, use a slide rule, or substitute numbers into equations to obtain results. The user does not even need to know the underlying equation the nomogram represents.