USE OF THE FOREST SERVICE STANDARD 



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2. An increase in the degree of error as recorded in reading the 

 hypsometer. The latter condition is true because the Forest Service 

 Standard Hypsometer reads in percents, and therefore the higher the 

 tree the greater the degree of error recorded on account of incorrect 

 horizontal distance. 



Since it appears essential that the same points from which the orig- 

 inal readings of trees were taken be relocated in making subsequent 

 measurements, attention is called to the following facts concerning the 

 use of the Forest Service Standard Hypsometer. By using the follow- 

 ing method, relocation of points is easily accomplished and the chances 

 for error due to conditions, as noted, are largely eliminated. While 



Fig. I 



absolute heights may not always be obtained, accurate record of 

 increase in growth will, however, be secured. 



The essential principle involved in the new method is, that instead 

 of it being necessary to stand exactly lOO feet, or multiple distances 

 thereof, away from the tree, any distance from which a good sight 

 can be secured may be used. Additional computation is, however, 

 necessary in order to obtain the correct heights, but this can be done in 

 the office after the field data have been secured. Since any distance 

 can be used for taking readings, several tree heights can be read from 

 the same point, and the relocation of this point is therefore readily ac- 

 complished when subsequent height measurements are to be made. 



The following example clearly illustrates the method of obtaining 

 data : 



