Lewis E. Waterman revolutionized writing by developing a relatively leak-proof fountain pen. It must be remembered that before Waterman came into the picture, pen tips had to be dipped in ink after every few words. During those days, Salesmen used to wear a vest chain with a small metal container holding a vial of ink in one pocket, and a collapsible penholder in the other. Waterman solved this problem by putting a sealed ink reservoir in the pen, above the pen?s metal nib (point). Waterman used capillary action to replace the ink in the rubber sac with air, to facilitate the ink to flow smoothly and not all at once. When he realised that the metal content in the ink dissolved the steel pen nib, he used an iridium-plated gold nib. He was also the first to place a clip on the pen cap.