1904 



FORESTRY AND IRRIGATION 



207 



COUNTING KINGS OK ANNUAL GROWTH WITH A LENS. 



pines and one at Washington under 

 different departments and having no 

 official connection. An explanation of 

 the work of the tropical bureau was 

 given in FORESTRY AND IRRIGATION 

 for April by Mr. Wilhehn Klemme. 



The work of the Bureau at Wash- 

 ington is divided conveniently as fol- 

 lows : Into preparation of working 

 plans, surveys of forest reserves, the 

 extension of forest .areas by planting 

 and otherwise, and investigation of for- 

 est products. Each of these branches 

 of work corresponds to an official divis- 

 ion of similar name. 



The most extensive branch of activity 

 is the preparation of working plans for 

 large tracts of forested lands. A work- 

 ing plan, it may be said, is a carefully 

 thought out scheme for the treatment 

 of a specified area of woodland, based 

 on a study of past and present condi- 

 tions of growth and designed so to sup- 

 plement and aid natural conditions that 

 the forest shall continually produce and 

 yield the largest quantity and the best 

 quality of wood possible. 



In order to make such a plan, two 

 main facts must be ascertained the 



present amount of wood standing and 

 the amount of increase by growth each 

 year. 



The observations which must be made 

 are of two kinds, known as forest sur- 

 veys and stem analyses. 



By means of the former the diameter 

 of the trees on about one-twentieth of 

 the total area is actually measuiedwith 

 large calipers. All the trees are cali- 

 pered 33 feet on each side of compass 

 lines run across the forest, either parallel 

 or in a zigzag manner from one side to 

 the other. Calipering thus for a mile 

 along the line covers 8 acres. From 

 such records may be' obtained an aver- 

 age of the entire area, which is believed 

 to vary by not more than one-tenth from 

 the actual stand. Wherever the com- 

 pass lines cross streams, strike the edge 

 of the timber, or traverse slopes, notes 

 of the distances are taken, which are 

 the data by which a very fairly accurate 

 timber map is drawn. 



Attention is also given to the value of 

 streams for driving, the chances for 

 splash-dams, camp sites, railways, and 

 roads, and a mass of information is thus 

 collected which may prove of the greatest 



