#### Victor Mayer Amedee Mannheim (1831~1906)

Although slide rules existed before Mannheim’s time, invented by Oughtred and Gunter and others, it was Mannheim who standardised the modern version of the slide rule which was in common use until pocket calculators took over a few years ago. It was while he was a student at Metz that the ideas for this slide rule came to Mannheim.

The modern standard Mannheim-type rule typically has scales that allow you to perform multiplication, division, squares, square roots, logs, sine, cosine, and tangent calculations. There are also many variants that include things like specialized scales for cubes and cube roots, and for making multiplication and division a bit easier (like an inverted C scale).

Key to understanding how to deal with the outcome of calculations is an understanding of the related concepts of precision and accuracy. These terms are often used interchangeably in common practice (alas!), but they actually refer to two critically different concepts. Technically speaking, accuracy refers to the degree of conformity of a measure to the actual, true value. Precision is simply the degree of refinement with which a measure can be taken or stated. So, for example, the number 0.98597632 is very precise, whereas the similar number 1.0 is much less precise. Notice, however, that a high degree of precision has a price - it assumes we can reliably get that number, over and over again, to at least half the value of the last digit.

After graduating from the École d’Applicationin Metz, Mannheim became an officer of the French artillery. After several years in the military, Mannheim was appointed to the École Polytechnique in Paris, while continuing his army career. His first appointment at the École Polytechnique in 1859, then in 1863 he was appointed as an examiner. In the following year Mannheim was appointed as Professor of Descriptive Geometry at the École Polytechnique. Koppelman writes in [1]:-

He was a dedicated and popular teacher, strongly devoted to the École Polytechnique, and was one of the founders of the Société Amicale des Anciens Elèves de l’École.

Mannheim retired from his army post in 1890, having attained the rank of colonel in the engineering corps. He continued teaching at the École Polytechnique until he retired in 1901 at the age of 70.