By Cy Tymony
Want to know the height of a person or building?
Using simple trigonometric principles, you can
closely estimate the height of objects with an easy-to-make hypsometer (hyps means height in Greek).
YOU WILL NEED
Large paper clip
1. Make it.
Tape the straw along the top of the card. Punch a
small hole in the right side of the card, 10cm from
the bottom. Straighten the paper clip, bend one end
into a small hook, and hang it in the hole so it swings
freely. Next, write numbers 0 to 12, 1cm apart, from
right to left across the bottom of the card, starting
with 0 directly beneath the hanging paper clip, proceeding leftward to 12. Here’s a tip: If you use a thick
plastic bag instead of the card, your hypsometer
can be rolled up and carried in your pocket.
Scissors and hole punch
6"× 8" piece of cardboard
or a thick plastic bag
Ruler with inch and
2. Test it.
Standing 10' away, look through the straw at the
top of a friend’s head. When you tilt your head (and
the hypsometer), the paper clip will move leftward
at an angle as gravity keeps it pointing down at the
ground. In Figure 2, it points to number 1.
By measuring your distance from an object (in
centimeters) and the angle of tilt indicated by your
hypsometer, you can calculate your friend’s height.
3. Calculate it.
You’ll need 2 more numbers for your calculation:
the height of the card (10cm), and the height of your
eye line, measured from the ground. You can also
measure from the top of your head, then subtract
this number from your height. For instance, if you’re
5' 8" tall and your eyes are 4" from the top of your
head, your eye line is 5' 4", or 164cm, off the ground.
Metric measurements are much easier to calculate with a hypsometer, because metric is a base 10
system. Use a metric ruler, or write equivalents on
your hypsometer as shown in Figure 3.
Multiply the distance to your friend ( 10' or 305cm)
by the angle number indicated by the paper clip ( 1),
then divide by the card height ( 10); in this case, you
get 30. 5. Add this to your eye line height (164cm),
for a total of 194.5cm. That’s about 6' 3" tall.
1 centimeter (cm) = 0.01 meter (m) = 0.4 inch (")
1" = 2.5cm
1 foot (') = 30cm
3. 3' = 1m
1,000m = 1 kilometer (km)
Distance to object (cm) × Angle number / 10
+ Height of eye line (cm)
= Height of object (cm)
Now test your hypsometer with objects of unknown
height, such as doors, walls, and buildings, to calibrate it and sharpen your measuring skills.
Cy Tymony is the author of the Sneaky Uses for Everyday
Things book series.
Illustrations by Julian Honoré/ p4rse.com
110 Make: Volume