106 



value of the angle secured, expressed as its tangent or percentage. 

 The tangent or percentage of this angle multiplied by the horizontal 

 distance from the observer to the tree gives the height of the tree 

 above the level of the observer's eye. He then sights to the base of 

 the tree, and in the same manner ascertains the angle formed by a 

 horizontal line running from him to the tree and a line running from 

 his eye to the base of the tree. He now consults his table again 

 for the value of this angle expressed as its tangent or percentage 

 and multiplies this value by his horizontal distance from the tree, 

 which gives the height of the tree from the ground to the level of 

 his eye. The figures thus secured are added together, giving the 

 total height of the tree. Cost, $13. 



The scales of the instrument are sometimes graduated in tan- 

 gents or percentages of angles instead of in degrees, in which case 

 the table of tangents is not needed. 



A number of other height measures are used in Europe, but a full 

 description of them is not given, as that would make this Hand- 

 book too voluminous. The most important instruments are the 

 Brandis height measure, the Weise height measure, the Christen 

 height measure, the Klaussner height measure, and the Winkler 

 height measure. 



Several instruments have been devised to measure the diameter 

 of a tree at any desired height. They are of practical use when 

 extremely accurate measurements of standing trees are desired, 

 but will probably not be extensively used by timber cruisers. The 

 names of these instruments are the Breymann dendrometer, the 

 Winkler dendrometer (combined with the Winkler height meas- 

 ure), and the Wimmenauer dendrometer. 



CALIPERS FOR MEASURING DIAMETERS. 



Calipers are supplied to the trade in a variety of forms, but the 

 form shown in fig. 12 is recommended for its simplicity. It con- 

 sists of a beam having a scale on both sides, graduated in inches 

 and tenths. This beam is provided at one end with an arm held 

 in place by a bolt and nut which permit it to be detached for con- 

 venience of transportation. The beam is provided also with a 

 sliding arm fitted loosely, so as to slide easily over it, but con- ' 



