Suunto PM-5/1520 Handbuch Seite 2

Suunto Height Meter PM-5/1520 is an istrument for measuring heights,
especially heights of trees, with great accuracy and speed.
The body of the instrument is corrosion-resistant anodized aluminium-
alloy. The scale card runs on a special bearing in a hermetically sealed
plastic container filled with a liquid which guarantees that it runs freely
and stops quickly. The liquid will not freeze, retains full damping properties
in working conditions and eliminates irritating scale vibrations.
INSTRUCTIONS FOR USE
When measured from distances of 15 m and 20 m, free heights can be read
straight off the instrument`s scales. The readings should be doubled when
measuring from distances of 30 m and 40 m.
The Suunto Height Meter can also be used to determine the angle of a
gradient. This is done by taking a sighting along the line of a gradient
using the 20 m scale of the 20 m scale of the left of the instrument. The
reading obtained can be conversion table on the back of the instrument.
MEASUREMENT OF HEIGHT
The actual measurement of the height of the tree should be done from
the distance measured as in paragraph above in the following way: the
observer sights the top of the tree with both eyes open (see front page).
The object sighted, the hair line and the scale will all be simultaneously
visible in the instrument`s field of vision. As soon as the hairline coincides
with the top of the tree, the tree height can be read off (in this example,
from the 20 m scale on the left of the instrument).
The reading obtained is the height of the tree measured from the eye level
of the observer. The base of the tree remains to be sighted. If this situated
below the eye level of the observer, then the actual height of the tree is
obtained by adding the two readings together (see fig. 1). If it is above
the observer`s eye level, the tree height is obtained by taking the difference
between the two readings (see fi. 2). (In fact, in the case of fig. 2 the
distance cannot be measured horizontally. Thus, to get exactly correct
result you have to proceed as stated below.)