Although the full development of the Stangenkunst came later, it was apparently introduced in Agricola's time. Its introduction to the Erzgebirge has been put as early as 1550.[14] According to another authority it was introduced to the Harz in 1565 by one Heinrich Eschenbach of Meissen.[15] Its significance is only made clear to us by later authorities. As shown in figure 3 it was adapted to the utilization of a distant stream, through the Feldstangen, an extended horizontal series of reciprocating rods, and the Kunstkreuz (fig. 6), a lever in the shape of a cross for changing at right angles the direction of power transmission. These improvements may have been almost contemporaneous with Agricola, as Calvoer mentions the use of the Feldkunst, which term signified the extended rods, as having been known in 1565. The disadvantage of moving the weight of a long extension of rods was obviated, during the 17th century, through the use of a double set of balanced rods, resembling a pantograph. At some later date the horse whim was fitted with a crank and adapted to the Stangenkunst,[16] thus permitting the establishment of a veritable power network, as suggested in figure 1. The Freiberg mine director Martin Planer reported in 1570 the installation since 1557 of thirty-eight "Kunsten und Zeugen" in mines under his charge. That these were water-powered machines is clear from his remark that their cost was only 10 to 20 percent that of "Pferden und Knechten."[17] It is likely that many if not most were Stangenkunsten, for mining treatises of the 17th and 18th centuries testify to the continuous extension of this mechanism.[18] Perhaps the most striking evidence of its importance is its representation on the illustrated coinage of the 17th century. These multiple talers (figs. 1, 2, 3), happy products of the ingenious fiscal policies of the Dukes of Brunswick, picture mining activity in the 17th century no less elegantly than do the woodcuts of _De re metallica_ a century earlier. The Stangenkunst received its most spectacular application in France, in its application to the driving of the second- and third-stage pumps in the famous waterworks at Marly (1681-88), but its real importance is better illustrated in central Europe, by the many descriptions and drawings showing its use in the mines, driving machinery as distant as a mile[19] from the source of power. [Illustration: Figure 7.--FELDGESTANGE (STANGENKUNST) NEAR LAUTENTAL. From C. Matschoss, _Technische Kulturdenkmal_, Munich, 1932.]