Henry Clifton Sorby (10 May 1826 – 9 March 1908) was an English microscopist and geologist. His major contribution was the development of techniques for studying iron and steel with microscopes. This paved the way for the mass production of steel. Biography Sorby was born at Woodbourne, near Sheffield in Yorkshire, and attended Sheffield Collegiate School. He early on developed an interest in natural science. One of his first papers related to the excavation of valleys in Yorkshire. In 1847, when he was 21, his father died, leaving him a comfortable private income. He immediately established a scientific laboratory and workshop at his home. He subsequently dealt with the physical geography of former geological periods, with the wave-structure in certain stratified rocks, and the origin of slaty cleavage. He took up the study of rocks and minerals under the microscope, and published an important memoir, "On the Microscopical Structure of Crystals", in 1858 (Quart. Journ. Geol. Soc.). In England, he was one of the pioneers in petrography; he was awarded the Wollaston medal by the Geological Society of London in 1869, and became its president. In his presidential addresses, Sorby gave the results of original research on the structure and origin of limestones and of non-calcareous stratified rocks (1879–1880). In 1863, he used etching with acid to study the microscopic structure of iron and steel. Using this technique, he was the first in England to understand that a small but precise quantity of carbon gave steel its strength. This paved the way for Henry Bessemer and Robert Forester Mushet to develop the method for mass-producing steel. Due to this accomplishment, Sorby is known to modern metallurgists as the "father of metallography", with an award bearing his name being offered by the International Metallographic Society for lifetime achievement. His interests were broad. He published essays on the construction and use of the micro-spectroscope in the study of animal and vegetable colouring matter and on the temperature of the water in estuaries. He also applied his skill in making preparations of invertebrate animals for lantern slides. Furthermore, he once estimated "one cubic thousandth of an inch of water to contain 3.7x10^15 molecules." He was president of the Royal Microscopical Society. In 1882, he was elected president of Firth College, Sheffield after the death of founder Mark Firth. Sorby also worked hard for the establishment of the University of Sheffield, which was eventually