Other branches than silviculture were similarly first treated in comprehensive volumes and then in monographic writings on special subjects of the branch. The literature on forest utilization covering the whole field, was enriched especially by Pfeil, Koenig, Gayer, and Fürst. The first investigation into the physical and technical properties of wood was conducted by G. L. Hartig himself, followed by Theodor Hartig, and the subject has been most broadly treated by H. Noerdlinger (1860). In later years, Schwappach’s investigations deserve special mention.
The question of means of transportation gradually became also a subject capable of monographic treatment and a series of books came out on locating and building forest roads. Braun issued such a book in 1855 for the plains country, and Kaiser (1873) for the mountains, also Mühlhausen (1876), who had been commissioned to locate a perfect road system over the demonstration forest at the forest academy of Muenden. Only within the last quarter of the century were railroads introduced into the economy of forest management. The first comprehensive book on the subject of logging railroads was issued by Foerster (1885), and a later one by Runnebaum. Stoetzer (1903) furnished in his compact style the latest discussion on the subject of roads and railroads.
A very comprehensive literature on the value of forest litter was brought into existence by the established usage of small farmers of supplying their lack of straw for bedding and manure by substituting the litter raked from the forest. Hartig and Hundeshagen were active in the discussion of this subject as well as almost every other forester, the discussion being, however, mainly based on opinions. But, after 1860, the subject became so important both to the poor farming population and to the forest, which was being robbed of its natural fertilizer, that a more definite basis for regulating its use was established by analysis and by experiments at the experimental stations.
With the inauguration of the various methods of forest organization described before, there naturally went hand in hand the development of methods of measurement. Better forest surveys developed rapidly, the transit generally replacing the compass and plane table. At this period the necessity for books teaching the important methods of land survey was met by Baur (1858) and by Krafft (1865). This subject does no longer occupy a place in forestry literature, the knowledge of it being taken for granted.
On the other hand the subject of forest mensuration which formerly was generally treated in connection with forest organization has developed into a branch by itself, and has been very considerably developed in its methods and instruments, making a tolerably accurate measurement of forest growth possible, although many unsolved problems are still under investigation. Still, late into the century it was customary to measure only circumferences of trees, by means of a chain or band, although an instrument for measuring diameters is mentioned by Cotta, in 1804, and by Hartig, in 1808. Schœner and Richter are in 1813 mentioned as inventors of the first “universal forest measure” or caliper. The improvement of calipers to their modern efficiency has been carried on since 1840 by Carl and Gustav Heyer and by many others until now self-recording calipers by (Reuss, Wimmenauer, etc.) have become practical instruments. For measuring the heights of trees, Hossfeld had already a satisfactory instrument in 1800; a very large number of improvements in great variety followed, with Faustmann’s mirror hypsometer probably in the lead. As a special development for measuring diameters at varying heights Pressler’s instrument should be mentioned, and a very complicated but extremely accurate one constructed by Breymann.
Various formulas for the computation of the contents of felled trees had already been developed by Oettelt and others in the eighteenth century and a formula by Huber, using the average area multiplied by length was definitely introduced in the Prussian practice in 1817. The names of Smalian, Hossfeld, Pressler and others are connected with improvements in these directions.
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.
For arriving at the volume of stands, estimating was relied upon long into the nineteenth century, although Hossfeld, in 1812, introduced measuring, and the use of the formula AHF, in which A was the measured total cross-section area of the stand, H and F the height and form factors, the latter being at that time still estimated. He first made form classes for the same heights, but, in 1823, simplified the method by assuming an average form factor for the whole stand. Even in 1830, Kœnig still estimated the form factor, although he introduced the measurement of the cross-section area and determined the height indirectly as an average of measurements of several height classes, but Huber (1824) knew how to measure both the average height and form factor by means of an arithmetic sample tree. This method found entrance into the practice and held sway until about 1860, when the well-known improvements by Draudt and Urich supplanted it. These last mentioned methods have become generally used in the practice, while other methods, like R. Hartig’s and Pressler’s, have remained mainly theoretical.