INSTRUMENTS USED IN MENSURATION. 



which the wood is submerged. Before and after immersion 

 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 submerging large quantities of wood, 

 the whole is first weighed, and only a fraction immersed. Let 

 the weight of the whole be = W, that of the immersed portion = w, 

 the volume of the former = F, of the latter v, then : 



W : w = V : v 

 and 



V = v - x W. 

 w 



Instead of having a graduated vessel, the latter ma} T be filled 

 up to an opening, then the wood is immersed, the outflowing 

 water caught in a separate vessel and measured (Fig. 20). 



