JONSON ABSOIvUTE FORM QUOTIENT 593 



The agreement between the actual measurements as given in the 

 bulletins and those obtained by applying the Jonson table is re- 

 markable. 



In my own field observations, I obtained the following general re- 

 sults in applying the form point to balsam, spruce, and jack pine in 

 Quebec Province. 



Determination of volume of white spruce from stem analysis in the 

 St. Maurice Region, Quebec, compared to estimates made on the trees 

 before they were felled (32 trees) : 



Average volume per tree, 22.75. 



Average form class as determined by direct measurements, 0.662. 



Average form class as determined by form point observations on 

 standing tree, 0.659. 



xA.verage volume per tree obtained from Jonson tables by using this 

 latter form class, 22.60. 



The estimated results are thus 0.66 per cent too low. 



A standing 10-per cent estimate made on a certain area intended for 

 pulpwood cutting gave 5,282,327 feet board measure and 262, 341. logs, 

 according to the Jonson taper tables. The actual scaling after the cut 

 gave 5,532,842 feet board measure and 259,631 logs. 



The estimated results had, therefore, an error of about 1 per cent 

 too high in the number of logs and 4.5 per cent too low in the volume. 



Such a result could, in my estimation, be considered exceptionally 

 accurate. However, it indicates a possibility. The Jonson taper 

 tables usually give close results. In such work, of course, the classi- 

 fying of trees in the tallying has also a very direct bearing on the 

 results. One should always be careful to take into consideration any 

 root deformation which extends as high as the breast height. The 

 Jonson forms follow a straight course downward past breast height. 

 Graphical analysis will show up any curving due to root swelling and 

 the d.b.h. could be reduced to the true proportion. A good rule to 

 follow is to take the d.b.h. a little higher when the root swelling is 

 suspected. 



As regards the form point determination the tendency is to take it 

 somewhat low. This would cause volume results to be if anything, 

 too low. However, this is a safe error in timber estimating. 



Apparently the Jonson system holds true when tried in American 

 forests. It is to be hoped that foresters will make use of it. One 

 may later find deviations from the rule but in my opinion these will 

 never be large enough to prevent its tmrestricted application for com- 

 mercial practice. 



There is much interest displayed bv certain foresters for the Jonson 

 Absolute Form Quotient system, in fact, a set of tables translated and 

 converted into English and English units is much desired. The work 

 of compiling and printing them is started. ^Vith the interest and col- 

 laboration of Professor jonson and others, it is to be hoped that these 

 tables will soon be completed, to facilitate the work of all those who 

 begin to apply the system in timber estimating and computations. 



