1883.] KAY'S DENDBOMETER. 21 



KAY'S DENDBOMETER. 



FOR MEASURING THE HEIGHT OF TREES OR ANY OTHER OBJECT. 



iHE principal advantages of tlii.s instrument, wliicli lias been 

 awarded a first-class silver medal by the Scottisli Arboricultural 

 Society, are the following : — First, its simplicity ; second, no 

 calculation is required ; third, the height of au object can be ob- 

 tained at any convenient distance ; and fourth, the height of any part 

 of a tree, such as length of bole, can be ascertained from one station. 



Construction. — The construction and application of the instru- 

 ment, which will be seen by the accompanying engraving (see Fig. 1) 

 is founded on the principles which apply to all right-angled triangles. 

 The side A. B. may be termed the base-line, or the distance the 

 •observer stands from the object the height of which he wishes to 

 ascertain. The horizontal lines at right angles to the base-line re- 

 present the altitudes or heights. The height of an object is shown 

 at the part where the plumb-line suspended from the point A. crosses 

 the line of altitude corresponding to the distance from the object on 

 the base-line ; and the numbers along the top and bottom show the 

 number of divisions corresponding to the altitude or height that the 

 plumb-line has arrived at on the line of altitude. 



The lines of altitude are drawn at every foot, and the base-line at 

 -every live feet, so that the observer can choose any convenient distance 

 from the object at every five feet.* 



The divisions may represent leet, links, or yards, but whatever 

 ■standard of measure is fixed on for the base-line, the altitude must 

 be understood to be the same. 



The divisions extend to 150, and thus represent a height of 150 

 ^eet ; but should it be found necessary at any time to measure a 

 greater height, the divisions may be termed yards when a height of 

 450 feet can be measured. 



Mode of Using. — Measure a base-line from the centre of the bole 

 of the tree of a length suitable for observing the height of the object, 

 and fix the staff in the ground at that point. Then, setting the 

 instrument in the direction of the object, turn the square till the 

 plumb-line falls right over the line A. B. (see Fig. 1). Fix the square 

 by the clamp screw and look through the sight C. A., and mark the 

 place on the object thus indicated as at B., Fig. 2. This will give 

 the level corresponding to the height of the observer. Next, slacken 

 the clamp screw and elevate the sight till it corresponds with the 

 highest point of the object, when the clamp screw is again fastened 

 and the height read off, the plumb-line showing the exact number of 



• The accompanying diagram being on a small £calo, the Unas are only d awn at the tens. 



