MEASUREMENT OF VOLUME WITH THE XYI,OMETER. 27 



the fact, that a sultmerged body displaces a vohime of water 

 equal to the volume of the body, and the instrument used is 

 called a xylometer. It consists of a graduated vessel, Fig. 19, 

 in which the wood is submerged. Before and after submersion, 

 the position of the water is noted, and the difference gives 

 directly the volume. The method is employed for the measure- 

 ment of irregular pieces, such as root wood and fagots. To 

 obviate the necessity of submergmg large quantities of wood, 

 the whole is first weighed, and only a portion submerged. 

 Let the weight of the whole be = W, that of the submerged 



Fig. 20. Fig. 19. 



portion = ir, the volume of the former = T', of the latter v, 

 W : ir = V : r 



then : 

 and 



T^ = - X ir. 



w 



Instead of having a graduated vessel, the latter may be 

 filled up to an opening, then the wood is submerged, the out- 

 flowing water caught in a separate vessel and measured 

 (Fig. 20). 



Note. — Pressler's Increment Borer can be obtained from 

 Herr Moritz Perles, Verlagshandlung, Wien, Austria ; Brandis' 

 Hypsometer from Herr Max Wolz, Bonn, Germany. All the 

 other instruments can be procured through Herr Wilhelm 

 Spoerhase, 37, Stein Strasse, Giessen, Germany. 



