- The American Civil War (allthetropes.org)
In 1861, a group of Southern states seceded from the American Union and declared themselves independent as the Confederate States of America. From there events took on a life of their own and the situation devolved into a full-blown war. The war was the result, like so many civil wars, of the failure of internal politics. In this case, the great failure was to resolve tensions over the future of Slavery in America; the ‘Slave States’ feared that the central government in Washington D.C. would attempt to regulate or ban the slave trade and the practice of slavery, an unjustified fear but one understandable in the context of the liberalization of the Northern Free States, where Anti-Slavery groups modeled after their British counterparts had begun to flourish.
- Cartesian coordinate system (Wikipedia)
In geometry, a Cartesian coordinate system (UK: /kɑːrˈtiːzjən/, US: /kɑːrˈtiːʒən/) in a plane is a coordinate system that specifies each point uniquely by a pair of real numbers called coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, called coordinate lines, coordinate axes or just axes (plural of axis) of the system. The point where they meet is called the origin and has (0, 0) as coordinates.