Periodical Literature. 497 



the influences upon it, the author tabulates the results of some 80 

 borings. 



He points out that in Sweden over 1,000 borers are in use — the 

 reviewer can attest that every forester he met there had his borer 

 handy and was on the qui vive to use it — and enlarges upon the 

 value of its uses for self education. "It belongs to a forester's 

 outfit as the plane to the carpenters," and whoever has once begun 

 to use it will, like the author, find such fascination in it as to make 

 its use a mania ! 



A few remarks on the increment per cent, according to Sch- 

 neider's formula explains the relative reliability of the latter. 



A table gives comparison of the detail of the various makes. 



A few hints regarding the use of the instrument are given. 

 Oiling (with fat pork) is not at all necessary in soft woods and 

 not absolutely necessary in hard woods but makes the work easier. 

 It is easiest to bore at the height of the elbow ; first bore horizontal 

 and to the center, with force but slowly as far as the thread goes, 

 then, when the instrument is solidly in, turn rapidly until towards 

 the end when the turning becomes slower ; then after a short back 

 turn introduce the needle, which is very easy in soft woods, in 

 hard woods requires some coaxing or rather trying for a place 

 where it goes readily. In 700 borings the author did not breaK a 

 needle. Close the bore hole with a twig end tightly. No un- 

 favorable results of the boring having been observed in 10 years. 

 Recording the cylinders and keeping them best in a flat pencil 

 case, and cleaning the instrument like a gun and careful protec- 

 tion of the cutting edge are also necessary. 



Neues und Altes voni Zuzuachshorer. Forstwissenschaftliches Central- 

 blatt. May, 191 1, pp. 247-268. 



The Russian Medwiedew, the originator of 

 Measure. the idea of relative height which he used to 



of determine relative tolerance of species, has 



Crown developed an interesting new method of 



Density. determining density classes by a careful in- 



vestigation. After a discussion of gener- 

 alities regarding height growth and influence of light and density 

 on development of stands, he comes to the conclusion that the 

 diameter increment in open position exceeds that in dense position 



