Night writing visited the National Institute for the Blind in Paris, France, where he met Louis Braille. Braille identified the major failing of the code, which was that the human finger could not encompass the whole symbol without moving and so could not move rapidly from one symbol to another. His modification was to use a six-dot cell, the Braille system that revolutionized written communication for the visually impaired. Night writing Night writing, a.k.a. sonography, was a system of code that used symbols of twelve dots arranged as two columns of six dots embossed on a square of paperboard, and is now
Point plotting Point plotting Point plotting is an elementary mathematical skill required in analytic geometry. Invented by René Descartes and originally used to locate positions on military maps, this skill is now assumed of everyone who wants to locate grid 7A on any map. Using point plotting, one associates an ordered pair of real numbers ("x", "y") with a point in the plane in a one-to-one manner. As a result, one obtains the 2-dimensional Cartesian coordinate system. To be able to plot points, one needs to first decide on a point in plane which will be called the "origin", and a couple