Colonization of the Congo of Hell. It was not until 1867 that the Congo was explored by Europeans, and even then it was not from the sea, but from the other side of the African continent. Setting out from Zanzibar, Henry Morton Stanley, a British-born American journalist and explorer aimed to find the famous Dr. Livingstone. Livingstone had not been heard from in several years and was, in fact, exploring the upper reaches of a great navigable inland river called the Lualaba, which Livingstone hoped was connected to the Nile, but which turned out to be the upper Congo. After leaving Livingstone, Stanley sailed
19th century in science later in the 19th century by the German mathematician Bernhard Riemann; here no parallel can be found and the angles in a triangle add up to more than 180°. Riemann also developed Riemannian geometry, which unifies and vastly generalizes the three types of geometry. The 19th century saw the beginning of a great deal of abstract algebra. Hermann Grassmann in Germany gave a first version of vector spaces, William Rowan Hamilton in Ireland developed noncommutative algebra. The British mathematician George Boole devised an algebra that soon evolved into what is now called Boolean algebra, in which the only numbers were