26 FOREST COMMISSIOXER'S REPORT. 



have clipped its northwest corner and burnt a small piece 

 along the outlet of Spencer pond. Water, swamp and blow- 

 down occupy a large proportion of the remaining area. Yet 

 the Pratt tract is considered one of the best pieces of timber 

 in the region. Anyone who listens to timber talk at Flag- 

 staff or Eustis will be sure to hear a lot about it. Its actual 

 condition is a striking comment on the way in which spruce 

 stands in this ]iortion of the State. 



Percentage ^ digression must here be made in order to 

 of growth, explain a method of investigation which was first 

 made use of on this tract. The determination of the per- 

 centage of growth of trees is a most important matter. 

 A method for that purpose ought to l)e in use among 

 lumbermen in determining their cutting policy. By its 

 means they could tell what timber is least thrifty, and 

 what, on the other hand, might well be left to grow. In 

 this study, the percentage of growth has a wide use, in 

 fact, it is at the bottom of its most far reachino; conclusions. 

 A method of obtaining it on large numbers of trees was 

 essential, a quick and handy method, less expensive and 

 laborious than the cutting down and sectioning of any con- 

 siderable number. 



Pressier's Such a method was at hand, devised by the Ger- 



tabies. j^^jjj^ Pressler. He constructed a bit, for the pur- 



pose of boring into a tree and taking out a little core of wood. 

 On this the thickness of any desired number of the yearly 

 rings can be measured, and the ratio of this to half the diame- 

 ter of the tree gives, with tables devised for the purpose, the 

 percentage of present growth. The correctness of the tables 

 of course is the crucial matter. They were calculated from 

 detail measurement of great numbers of trees, the way in 

 which the yearly layer of wood is put on being minutely taken 

 into account. More assuring, perhaps, is the fact that their 

 availability for use on our own trees has been tested in the 

 course of this present investigation. About sixty trees were 

 at one time and another, in the course of the season, chopped 

 down and subjected to careful measurement. The figures 



