The Cambridge History of English and American Literature in 18 Volumes (1907–21). Volume XIV. The Victorian Age, Part Two. VIII. The Literature of Science. § 46. Sorby. Henry Clifton Sorby made his mark in more than one department of science, to which a sufficiency of income enabled him to devote his life; but he will always be remembered as the father of microscopic petrology. Thin slices of hard bodies had already been made for examination under the microscope; but Sorby was the first to perceive the value of this method for the examination of rocks in general. In 1849, he made the first transparent section of one with his own hands, publishing his first petrographical study in 1851. In a few years, his example had been followed both in England and in other countries, and the result has been a vast increase in our knowledge of the mineral composition and structures of rocks, and of many difficult problems in their history.   121