The metallurgical revolution of increased supply and decreased cost followed three stages: 1) coke use in the blast furnace, 2) puddling process for wrought iron (WI) and 3) Bessemer or Siemens processes for steel. The second gave rise to the conversion from wooden (iron-reinforced) machines to iron machines such as railroad engines, ships and long-span bridges, all hot-riveted. The self-made mechanical engineers raised the precision, scale and speed of mechanical shaping technology; this was transferred from WI to ingot steel with little difficulty for the same products with increased strength. Accurately measured mechanical properties of WI and steel were related for the first time to microstructure and processing by David Kirkaldy to improve Clyde-built ships and to propel metallurgy from artisanal to science-based.