Alma record. (Alma, Mich.) 1878-1928, 1889-12-06

OF mathematics, have often felt the
Importance of knowing some convenient
and simple method for determining the
hight OF tree or the width OF a
stream, and 10 whom such knowledge
would be very useful and desirable.
The hight OF a tree may be estima-
ted sufficiently exact for ordinary pur-
poses by the following method: Being
in the vicinity OF a tree, the hight OF
which you may wish TO know. and in
your hand you carry walking-cane or
a jointed fishing rod, and supposing
the cane or a length OF the rod is just
three feet, set il in the ground verti-
cally, and If the sun shines, il will
cast a shadow; now, with a pocket
rule, you measure the length OF the
shadow and find it, say two feet.
Here, then, we have n right angle OF
two feet and three feet. Now measure
from the base OF the tree TO the end OF
It's shadow. and we will suppose ii u
be twenty feet The problem, there
fore, is simply this: Ii cane three
feet high casts shadow OF two feet,
how high must tree be To cast a
shadow Of twenty feetP Or, in other
words, If two gives three, how much
will twenty give? BY the simple
"rule of three" we find the answer to
be thirty feet. Thus. by similar
triangles, we have 2:3:20:X. 40
feet-the trees hight.
But the reader may now ask: Sup
pose the sun doesn't shine, what then?n
Why, then set up the cane as before,
say eighteen feet from the base of the
tree. Now place your head on the
ground, with the cane between youand
the tree, moving nearer TO or farther
from it. until you can just see the top
OF the cane; then place a pebble or
mark on the ground at the point where
you obtain this view. The cane being
three feet high, the distance from the
pebble TO it will be two feet, aud from
the pebble to the base of the tree.
twenty feet, hence, by the same rule. We
find the height of the tree 10 be thirty
feet, as explained above.
The following method with little
practice, will enable any person TO
measure the heights OF trees or other
objects with approximate accuracy
when the sun is not shining, and the
method here given represents the
simplest and quickest way TO measure
heights, though the results are not alb
solutely correct
First make mark on the tree or
other object, say six feet from the
ground, or place pole six feet up
right against it. Then walk away TO
such distance that the breadth OF the
hand, held out at full arms length,
will just cover the six feet. Mark
with the eye point on the tree at the
upper end OF the six feet, and move
the hand upwards another breadth, and
thus proceed until the whole height is
measured. 1t may sometimes be con-
venient for an assistant TO stand at the
foot OF the tree, and If when his hat is
on he will be six feet high. he may
serve as a measure to begin with
instead of the rod. 1t is well to stand
at some distance from the tree in
making these measurements, or other
wise the upper measured proportions
will be larger than the lower on ac-
count OF the longer legs" of the
imaginary triangle. If the distance
be too great for the breadth OF the
hand, one or two fingers only may be
used. or short pocket rule. Or. if
the pocket rule be used, its separate
subdivision into inches may be made to
indicate the proportions measured, and
the whole completed at measurement.