5.
Steel nibs made possible the development of fountain pens, and the first successful models began to appear in the 1880s. In the fountain pen a slim rubber sac kept ink supplied to the nib. Although the fountain pen was a technical advance, it was not popular at first. But as public education became more widespread, more and more people bought pens. World War I also helped boost sales. Many soldiers used fountain pens for writing letters home. By 1925 twenty-five million fountain pens a year were being made in the United States alone.