A PRACTICAL XYLOMETER 



By J. S. Illick 

 Acting Director, Pennsylvania State Forest Academy 



Practical and precise instruments are an essential feature of any ^ood 

 business. They are especially serviceable during the formative period 

 of a business, when efforts are directed primarily towards building up 

 a body of exact knowledge which, as a rule, is a potent determinant 

 factor of future development. The present need of such a body of 

 exact knowledge is nowhere greater and more urgent than in the prac- 

 tice of Ainerican forestry. In order to satisfy this impending want, a 

 comprehensive series of systematic forest investigations should be in- 

 stituted at once, for it is only by this means that a durable foundation 

 of rational forest development can be laid. Such a procedure requires 

 not only able investigators, but also a full equipment of modern scien- 

 tific appliances. 



.\ practical xylometer is an indispensable part of the equipment of a 

 forest investigator working upon problems requiring an accurate deter- 

 mination of volume. The limited use of xylometers in the past may 

 be largely attributed to their impractical construction and the conse- 

 quent difificulty of loading and unloading them. During the past five 

 years the writer has been using a xylometer which, on account of its 

 practicability, deserves a more extensive use. It has given satisfaction 

 in tree analysis work and in growth and yield studies, particularly in 

 determining the contents of mean sample trees in second-growth stands, 

 and it has been especially serviceable in determining the waste factor 

 of portable sawmills, shingle mills, lathe mills, and logging operations. 



The principle of operation is alike in all x3'lometers. It is based 

 upon the fact that a submerged body displaces a volume of water equal 

 to its own solid contents. The method of ascertaining the volume 

 varies with the type of instrument used. Two types are generally rec- 

 ognized, viz.. graduated and ungraduated. Graduated xylometers are 

 only partly filled with water, whose position before and after submer- 

 sion is noted, and the difference represents the volume of the submerged 

 wood material. On the other hand, ungraduated xylometers are com- 

 pletely filled up with water to an opening or overflow, then the wood 

 material is submerged, and the displaced volume of water escaping 



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