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The Philamath's Alphabet-M M athematics teaching Many

stamps feature the teaching of mathematics. This stamp, issued by Guinea-Bissau for the International Year of the Child, illustrates the teach- ing of the geometry of a circle; Maxwel r s equat ions Using the most advanced vector methods of his day, James Clerk Maxwell (1831-1879) syn- thesized Faraday's laws of electro- magnetism into a coherent mathe- matical theory, confirming Faraday's intuition that light consists of electro- magnetic waves. His celebrated Trea- tise on electricity and magnetism, containing the fundamental mathemat- ical laws now known as 'Maxwelrs

equations', predicted the existence of such phenomena as radio waves. Mayan mathematics The Mayans of Central America (300-1000 AD) used a counting system based on the numbers 20 and 18. Most of their mathematical calculations involved the construction of calendars: a 260-day ritual one with 13 cycles of 20 days, and a 365-day one with 18 months of 20 days and five ex- tra days: combining these gave a 'cal- endar-round' of 18980 days. Only a handful of Mayan manuscripts have survived, most notably the Dresden codex, painted in colour on fig-tree bark and containing many examples of Mayan numbers. Metric system Throughout the cen- turies various counting systems have been used for weights and measures. After the French Revolution, a com- mission was set up to investigate the desirability of a metric system for France; the chairman of this commis- sion was Joseph-Louis Lagrange. This

stamp shows an allegorical figure rep- resenting the French metric system. Miibius s t r ip The M6bius strip was named after the German mathemati- cian and astronomer August MSbius in 1858. It has only one side and one boundary edge, and is constructed from a rectangular strip of paper by identifying its ends in opposite direc- tions. M6bius was not the first to dis- cover it---Johann Benedict Listing beat him by a few months. Monge Gaspard Monge (1746-1818) taught at the military school in M6z- i~res. While investigating positionings for gun emplacements in a fortress, he improved the known methods for pro- jecting three-dimensional objects on to a plane; this subject became known as 'descriptive geometry'. Monge's other interests included 'differential geome- try', in which calculus is used to study curves drawn on surfaces, and he wrote the first important textbook on the subject.

Please send all submissions to the Stamp Corner Editor, Robin Wilson, Faculty of Mathematics, The Open University, Milton Keynes, MK7 6AA, England e-mail: r.j.wilson@open.ac.uk

76 THE MATHEMATICAL INTELLIGENCER �9 2006 Springer Science+ Business Media, Inc.