One of the ironies of invention is that in order for the inventor to receive recognition for a new discovery, it must be made public at the risk, patent or no patent, of being copied. William Kelly was first to develop the pneumatic conversion process for making steel. Yet he decided to keep it a secret, and credit for its discovery was given to Sir Henry Bessemer a few years later.

William Kelly was born in Pittsburgh, Pennsylvania, on August 21, 1811. He was engaged in the dry goods business in Philadelphia until 1846, when he moved to Eddyville, a small town in western Kentucky, to operate a sugar kettle foundry with his brother. The foundry used the centuries-old process of heating and hammering to work out the impurities in the iron. A shortage of charcoal forced Kelly to search for a more efficient forging process. In 1851 he developed a method of burning off carbon from iron at a faster rate by directing blasts of air at the molten iron. By this method, he was able to develop a low grade of steel.

Instead of protecting his conversion process with a patent, Kelly chose to keep it secret and went on to build several more furnaces. In 1856 Sir Henry Bessemer patented the same process in England, completely unaware of Kelly's work. Hearing of this, Kelly finally came forward and received an American patent in 1857.

Although he could prove that he was the first to discover the process, his delay cost him the notoriety (and much of the profit) he would otherwise have earned. The process became better known as the Bessemer conversion process, and within less than a decade, Kelly's steelmaking business in the United States was overtaken by Bessemer-related interests. Kelly spent the remainder of his years in obscurity, running an axe factor in Louisville, Kentucky, while his English counterpart went on to enjoy fame and wealth. Kelly died in Louisville on February 11, 1888.