 Complete the following phrase:  Malling-Hansen developed his Hansen Writing Ball further throughout the 1870s and 80s, and in 1874 he patented a new model jointly in which the cylinder was replaced by a flat carriage on which the paper was fastened. In 1875, the writing ball found its well-known tall shape. With this model, he found a mechanical solution for the movement of the paper, dispensing with the battery. The writing ball was sold in many countries in Europe, but probably due to the relatively high price, it was never a great commercial success. Even so, it was a great success in different exhibitions, Malling-Hansen and Halll, received the first prize medal at a large industrial exhibition in Copenhagen in 1872, and at the world exhibitions in Vienna in 1873, as well as in 