a) Physical form caliper
Physical form calipers in the form of bar that has a scale (unit of measurement) that is equipped with sliding sleeves. The sliding sleeve has a function as a reader on the scale of the crossbar. The units of measurement used is cm with the smallest unit of measurement in millimeters.
b) Basic Work
Because the sliding sleeve can be removable on the ruler scale, then the arm will slide directly indicate the amount of stem diameter as measured by reading the scale on the ruler. How do I use this caliper? For details, see Figure 35 and 36.
Figure 35. Measurement of tree diameter using a caliper
Figure 36. How to use calipers
Technical measurement using a caliper trunk diameters are:
(A) Apitkan both arms equally high on the face of the land (at breast height = 130 cm).
(B) Determine the shortest part of the girth (d1) as a measurement of the diameter of the first.
(C) Measurement of the second diameter (d2), perpendicular to the first measurement of the diameter or longest diameter.
(D) The diameter of the tree trunk is the average of both, namely:
c) Error measuring around a tree trunk
Measurement error due to both arms flanking a tree trunk is not as high or is not parallel to the horizontal plane. Errors that formed a circle stems will form an ellipse (Figure 37). So that measuring errors obtained at Ed = d2 – d1.
Figure 37. Error measure on the use of calipers