Leading Foresters. 101 



the methods of determining the cost value of stands. 

 His "Forest Mathematics" (1835) in which he intro- 

 duces factors of form and many other new ideas was 

 an original contribution to science. 



Very different in character from these four leaders 

 was the aggressive, sharp-witted Friedrich Wilhelm 

 Leopold Pfeil (1783-1859), who, without a university 

 education, and in spite of his poor knowledge of mathe- 

 matics and natural history, advanced himself by 

 native wit and genius. After a brief period of em- 

 ployment in private service, in the province of Silesia, 

 he accepted the position of professor of forestry at 

 the Berlin University, in 1821, in connection with 

 Hartig, with whom, however, he was at sword's 

 point. It was at his instigation, with the assistance 

 of von Humboldt, that the school was transferred, 

 in 1830, to Eberswalde, Pfeil becoming its director. 



While Hartig was a generalizer, Pfeil was an indi- 

 vidualizer, free from dogma, and most suggestive; 

 a free lance and a fighter. Critical in the extreme 

 and prolific in his literary work, he domineered the 

 forestry literature of the day by means of his Kritische 

 Blaetter, a journal of much import and merit. 



The youngest of the group, Karl Heyer (1797- 

 1856), a thoroughly educated man, combined the 

 professorial position in the University of Giessen 

 (1835) with practical management of a forest district, 

 but in 1834 abandoned the latter in order to devote 

 himself entirely to literary work. He was one of the 

 clearest and most systematic expounders, and both 

 his Waldbau (silviculture, 1854) and his Walder- 

 tragsregelung (forest organization, 1841) are classics. 



