Graphic by the Author.
Many
of you know the woodsman’s trick of estimating time by counting the number of
finger-widths between the local horizon and the Sun, (for more on this read “Estimating
The Time Till Sunset ©”, HERE),
some of you don’t, and most people don’t know that they can use their fingers
to measure more than just the time.
Estimating Degrees...
Measuring angles and estimating degrees with your hands, photograph by the Author.
Astronomers
measure the night sky in degrees of angular separation. Since there are 360o in a circle, the
degrees of angular separation between any point on the horizon to a point
halfway between the horizon and directly overhead is 45o, and to a
point directly overhead, or at the zenith, 90o.
You
can use your fingers and your hands to estimate the degrees between objects in
the sky, just like astronomers. With
your arm is fully extended, hold out your hand and close one eye. Now holding your hand like in the picture
above, estimate the degrees of separation between objects you are looking at. Don’t forget you can use two hands to combine
distances, so one fist and three fingers equals 15o (three fingers,
or 5o, plus one fist, or 10o, equals a total of 15o)
of angular separation.
Adapted by the Author from The Air Ministry Survival Guide, page 111.
Knowing
how to estimate the degrees of angular separation is especially useful when you
are trying to find the North Star, or Polaris.
The angular distance between the two pointer stars of the “Big Dipper”1, Merak and Dubhe, is
about 5o or the thickness of your index, middle and ring finger
combined. Count five times the distance
between the two pointer stars, or 25o, and you will find the North
Star. This is a very good way of
estimating the distance between the two, as the actual distance between Dubhe
and Polaris is 28o.
An excerpt from “A ‘Handy’ Way To Measure The Sky”, by NC Science Festival, HERE.
Thumbs, fists,
and distance...
Estimating distances with your thumbs and fists, photograph by the Author.
Your
fist is about 3 inches (7.6 cm) long, pinky knuckle to index finger knuckle, and
the thickness of the first knuckle of your thumb is about 1 inch (2.5 cm),
while the height of your thumb from its tip to the second knuckle is about 2
inches (5 cm) long. By knowing this you can
use your hands to estimate distances in feet and meters here on earth, just
like astronomers use their hands to estimate the distance between objects in
the night sky. All it takes is a little
math and holding your arm out, fully extended, closing one eye, and sticking
out your thumb, like in the picture above.
Now look at the object whose distance away from you, you want to
estimate, and count how many thumbs or fists high or long it is.
You
can use the chart below to help you, just pick a fist, an upright or sideways
thumb and read across to the right to find the distance multiplier; times 6
feet, times 15 feet, times 30 feet, etc.
If
you don’t have the chart handy, just remember that when holding your thumb sideways,
it has a multiplier of 30 feet, or 9 meters, and each time you halve the height
of your sideways thumb, the multiplier doubles: if you double the height of
your sideways thumb, the multiplier halves.
Graphic by the Author.
Now,
with your thumb sideways, point your arm at a nearby house window. You notice that the window is two sideways
thumbs tall. Knowing this and remembering
that your thumb, when held sideways, at arm’s length, has a 30 foot multiplier,
knowing the approximate height of the window, and using a little math, you can estimate
how far away the house is.
Graphic by the Author.
So,
the window you are looking at seems to be two sideways thumbs tall, and since windows
are approximately 4 feet, or 1.2 meters tall and a sideways thumb has a 30 foot
multiplier, the house is about 60 feet, or 18 meters away from you (2 times 30
equals 60 feet).
Know
all you need to know is the average size of things, and you can estimate
distance with the best of them.
Graphic by the Author.
I
hope that this helps you, next time you are out in the wilderness.
Don’t forget to come back next week and read “Goose Feathers!©”, where
we will talk about how to tell if you found a goose feather or a raptor
feather!
I
hope that you continue to enjoy The Woodsman’s Journal Online and look for me
on YouTube at BandanaMan Productions for other related videos, HERE. Don’t forget to follow me on both The
Woodsman’s Journal Online, HERE,
and subscribe to BandanaMan Productions on YouTube. If you have questions, as always, feel free
to leave a comment on either site. I
announce new articles on Facebook at Eric Reynolds, on Instagram at
bandanamanaproductions, and on VK at Eric Reynolds, so watch for me.
That
is all for now, and as always, until next time, Happy Trails!
Notes
1 The
“Big Dipper”, is also called Ursa
Major, the “Great Bear”, or in the United Kingdom, “The Plough”.
Sources
Air
Ministry, The Air Ministry Survival Guide, [Michael Joseph, Penguin
Random House, UK, 2018], pages 111-113
Body Ruler; “Measuring
Angle and Distance with your Thumb”, http://www.vendian.org/mncharity/dir3/bodyruler_angle/,
August 23, 2022
MathIsFun; “Estimate How
Far Away”, [© 2017 MathsIsFun.com], https://www.mathsisfun.com/measure/estimate-distance.html,
August 23, 2022,
NC Science Festival, “A
‘Handy’ Way To Measure The Sky”, [© 2016 The University of North Carolina at
Chapel Hill], https://ncsciencefestival.org/sites/default/files/documents/SSP_Handy%20Way%20to%20Measure%20the%20Sky.pdf,
August 31, 2022
Skwarecki, Beth; “How to
Estimate Distance Using Just Your Thumb”, August 3, 2022, [© 2022 G/O Media
Inc.], https://lifehacker.com/how-to-estimate-distance-using-just-your-thumb-1849365952,
August 23, 2022
Shepard, Lesley; “How to
Estimate Measurements Without a Ruler or Tape Measure”, October 6, 2019, [The
Spruce Crafts is part of the Dotdash Meredith publishing family], https://www.thesprucecrafts.com/ways-to-measure-without-ruler-2366642,
August 23, 2022
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