Build a clinometer
It measures how steeply you are looking up. Buildings, trees, flagpoles, and the stars.
You need
- this page, printed at 100%
- stiff card: the back of a notepad, or foam board
- a glue stick and some tape
- a drinking straw, the wider the better
- thread or dental floss, about 25 cm
- a nut, a washer or a heavy bead
- a pin, to make the hole
- scissors
The scale
Hold a ruler against the bar: it must measure exactly 50 mm. If it does not, print again at 100% with no scaling.
Put it together
- Glue the scale onto the card and cut round the outline.
- Tape the straw along the straight top edge, right along the line marked for it. It must not overhang the edge at an angle.
- Push the pin through the small circle at the middle of the top edge.
- Thread the string through the hole and knot it behind the card.
- Tie the nut on so it hangs about 3 cm below the curved edge.
Use it
- Look through the straw with one eye at the very top of the thing.
- Tip the card very slightly away from you, so the string hangs free and does not drag on it.
- Let the string stop swinging, then pinch it against the card and read the number it lies across.
- Do it three times and keep the middle reading.
- Write down how high your eye is off the ground. You will need it.
Check it before you trust it
Stand a long way back from a window ledge or a table edge that is at the height of your eye, and look along it through the straw. The string should lie across 0. If it lies across 1 or 2, write that down and take it off every reading you make.
At night
Find the star at the end of the handle of the Little Dipper, the one that stays put while the others turn round it. Sight it through the straw and read the string. That number is close to how far north of the equator you are standing, in degrees.
A wide straw helps. Find the star above the straw first, then bring your eye down to look along it.