12 



A new Dendrometer. 



quadrant. And, in practice, the instrument should be placed 

 exactly fifty feet from the tree to be measured, the calculations 

 being made for that distance ; the quadrant is to be placed 

 with\he index at o, and the sights so as to form part of a line 

 that will touch the left side of the tree at the place where the 

 diameter is wanted ; the degree of elevation being noted, the 

 slider supporting the quadrant should be moved from left to 

 rioht, till the sights on the quadrant form part of a line touch- 

 ing the opposite side of the tree. The space travelled over 

 b\Tthe index will be the exact diameter, and on the opposite 

 lines, on the near side, will be seen the corresponding circum- 

 ference and side of the square ; and at the same time, opposite 

 to the degree of elevation, will be seen the height of the point 

 where the diameter was taken. The following figure (6.) 



/Ik 



/ mi 



MkW. 



will illustrate the mode of operation. The instrument is 

 placed on an uneven surface fifty feet from the tree. The 

 plumb of the quadrant touching o gives a level from the 

 instrument, below which point the tree measures six feet. The 

 first angle of elevation taken is 15°, which, by looking at the 

 table on the quadrant, gives 13 feet 4-f inches. The next 

 angle is 25°, which gives 23 feet S| inches, which, by sub- 

 tracting the last height, leaves 9 feet lOf inches for the length 

 of the intermediate piece. In the same way the length of the 



