The idea of _form factors_ and their use was first developed by _Huber_, who made three tree classes according to the length of crowns, measured the diameters six feet above ground, and used reduction factors of .75, .66, .50 for the three classes. But the first formula for determining form factors is credited to _Hossfeld_ (1812). _Hundeshagen_ and _Koenig_ also occupied themselves with elaborating form factors. _Smalian_ (1837) introduced the conception of the _normal_ or true form factor relating it to the area at one-twentieth of the height. An entirely new idea has lately been introduced by _Schiffel_, an Austrian German, under the name of form quotient, placing two measured diameters in relation. _Volume tables_ giving the volumes of trees of varying diameters and height were already in use to some extent in the 18th century; _Cotta_ gives such for beech in 1804, and, in 1817, furnished a new set of so-called normal tables which were, however, based upon the assumption of a conical form of the tree. _Koenig_ perfected volume tables by introducing further classification into five growth classes (1813), published volume tables for beech and other species, and, in 1840, published volume tables not for single trees but for entire stands per acre classified by species, height and density; using the so-called space number which he had developed in 1835 to denote the density. It is interesting to note that these tables, which he called _Allgemeine Waldschætzungstafeln_, were made for the Imperial Russian Society for the Advancement of Forestry. In 1840 and succeeding years, the Bavarian government issued a comprehensive series of measurements and a large number of form factors, which were used in constructing volume tables; these were found to be so well made and so generally applicable that they were used in all parts of Germany and, translated into meter measurement by _Behm_ (1872), are still generally in use, although new ones based upon further measurements have been furnished by _Lorey_ and _Kuntze_.