Middletown transcript., 1916-07-22

buSlt AOt
prepared by the United States Depart
ment of Agriculture9
With the simple homemade instru-
ment illustrated herewith it is a very
easy matter to measure the height of
any tree provided one can get view
of it's top from u point 80 or 100
feet from its base. 1t is the instru-
ment which the Forest Service, in
Farmers Bulletin 715 recommends to
farmers who are thinking of selling
timber from woodlots and who wish to
base their sale upon the actual amount
of timber rather than upon guess work
or mere acreage basis.
Making the instrument.
AS accuracy in drawing parallel
lines, laying off right angles, and meas
uring distances is extremely impOr-
tant, those making the instrument
would do well to provide themselves
with a good steel square accurately
ruled for inches and quarter inches.
Take a piece of half-inch board by
8 inches and plane it smooth on all
sides. Draw the line ALB, three eighths
of an inch from the lower edge and pa
rallel to it. Two inches from the left
end of the board draw CD, at an exact
right angle to ALB. Make a mark at E,
6M inches from D, and another at F,
31s from D. Now draw line JK
through F, exactly parallel to ALB.
Starting at D, lay off accurately
inches and quarter inches ALB on both
directions, marking d as zero and put
ting down the number of inches from
D for each inch mark. Do the same
for the line JK. Then mark the scales
as indicated in the illustration, the fig
ures above the line being for feet and
those below the scale for the number
of 16-foot logs on the merchantable
part of the trunk. 1t will be seen that
each quarter inch on either of the pa
rallel lines represents 4 feet in height
and each line represents log 16 feet
long.
To Make Sights.
Take q brad or small nail and drive
it in carefully on the line JK about an
inch from the edge of the board. Drive
it in until the point comes out on the
back of the board; then pull it out and
drive it in from the back until the point
sticks out about One-fourth inch from
the face of the board. File off or
cut off with pliers any part of the
brad that projects from the back of
the board. In the same way insert an
other brad near the other end of the
line JK. 1t is important that the brads
or sights be straight and true.
To Make Pendulum.
Now take a piece of straight, heavy
wire 10 inches long, and bend one end
of it into q loop about an eighth of
an inch in diameter. Be certain that
the center of the loop of the wire is in
an exact line with the straight part
of the wire. FaSten this piece of
wire loosely to the board at E with a
half-inch screw, so that it will swing
| freely when the board is on edge. The
loop should be big enough to fit loose
ly over the shank of the screw, but
small enough so that it will not slip
off over the head.
Screw a piece of wood about six
inches long, one inch wide and a half
inch thick to the back of the board
to serve as a handle, and the height
measure is complete.
Using the Instrument.
m - - Aa1
tree, stand exactly 100 feet from its
base. Hold the instrument in the right
hand in such way that the pendulum
swings freely but very near the board.
Sight along the brads at the top of the
tree and let the pendulum come to
rest. Then with the left hand press
the pendulum against the board with
out giving it a chance to change its
position. The pendulum may also be
kept in position by fitting the right
| hand slightly to the right. This brings
the wire against the board and holds
it in place so that reading can be OBJ
tained. Care should be taken that the
wire does not slip after the board is
tilted.
Now read off the number of feet in
height OH the lower scale. If the wire
crosses the line five inches from the
point D, it indicates that the tree is
so feet high above the level of the eye
Without changing position, next
sight at the foot of the tree and take
the second reading. If in the second
reading the pendulum hangs to the left
of D, that is, between A and D, add
the amount indicated to the first read.
ing, and the result will be the total
height of the tree. Thus, if it hangs
half an inch to the left of D. add eight
feet to the first reading, making total
of IS feet. If, however, the eye is be-
low the foot of the tree, the wire will
hang to the right of D (between D and
| P) and the amd41nt of the second read.