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(Now part of AView from the Back of the Envelope.)The idea: you can measure with your body.
Length, angle, time, etc. This page deals with length.
And.. you will never forget to bring your bodyruler with you. :) Though sometimes I forget my calibration..
Length, angle, time, etc. This page deals with length.
And.. you will never forget to bring your bodyruler with you. :) Though sometimes I forget my calibration..
Your Body Ruler
A User's Manual
A User's Manual
Congratulations on being a human ruler!
Throughout history, people have been using themselves to measure length.You can too!
An example
How big is the screen/paper in front of you?My screen is about 4.5 palms by 3.5 palms.
(Yes, there are now fingerprints on my screen. :)
Gobdocuments 1 6 Cm Berapa
Having calibrated myself, I know my palm is 0.07 meters (7 cm, 2.75 in).
So my screen is something like 0.31 by 0.24 m (12.4 by 9.6 in).
Measuring with an 'ordinary ruler', I get 0.32 m and 0.25 m. (12.5by 9.5 in.)
So my palms quickly gave a nice measurement.
Gobdocuments 1 6 Cm Equals
Calibrating Yourself
A first step is to choose your measures, and measure your choices.Many body distances can be used as measures, but you dont need all ofthem. Many have similar size (for example, hand and palm), so you canjust choose ones you prefer, perhaps ones with numbers easier toremember. Also, some are related (1 palm can be 4 fingers). Feel free to use other measures, or to modify these (likeusing little finger rather than middle finger). The important thingis consistency, using them the same way each time.
Before using any new measuring instrument, one needs to calibrate itby comparing it with something else, something of known measure. Foryour bodyruler, you can use an 'ordinary ruler'. Averaging can beused to reduce error. For instance, measure out 3 palms and divide by3, rather than just measuring a single palm.
Here are some measures you might use. I'vehighlighted my favorites, and included some romannames.
Measure | Explanation | my personal calibration Your's will differ. |
finger | finger width (digitus) | 2 cm, 3/4 in |
'nail' | width of thumb's nail. (It's about finger width.) ('nail' historically also names some longer units.) | 1.5 cm, 5/8 in |
inch | thumb width, 'mesouret at the rut of the nayll' | 2.5 cm, 1 in |
half finger | fingertip to (middle of) second joint (choose a finger (historically, it was middle)) | 5.5 cm, 2 1/8 in |
finger length | fingertip to knuckle | 11 cm, 4 1/4 in |
palm | width of 4 extended fingers (palmus) ('palm' is also know as 'hand'.) | 7 cm, 2 3/4 in (at middle joint) 8 cm, 3 in (at knuckles) |
hand length | hand length, heel to fingertip | 19 cm, 7.5 in |
hand span | hand width, from outspread thumb to little-finger (Convenient, but because stretch varies, a bit less consistent than these others.) | 22 cm, 8.5 in |
foot | foot length, heel to toe (pes) Good for walking short distances. | 27 cm, 10.5 in (bare) 30 cm, 12 in (sneakers) |
cubit | elbow to fingertip (cubitus) | 47 cm, 18.5 in (~0.5 meter) |
yard | nose to fingertip, with arm straight out to side, head facing front Good for measuring rope and fabric. | 92 cm, 36 in (3 ft) (1 meter if I turn my head) |
fathom | fingertip to fingertip, arms out stretched | 178 cm, 68 in |
height | the usual | 182 cm, 72 in |
step | one step | ~80 cm, ~30 in (~3 ft) |
pace | two steps (passus) Good for walking long distances. | ~150 cm, ~60 in (~1.5 meter) |
Stuff
Gobdocuments 1 6 Cm Inches
Leonardo da Vinci (1452-1519) writes of Roman architect-engineerVitruvius Pollio (1st century B.C.):'.. Vitruvius declares that Nature has thus arranged themeasurements of a man: four fingers make one palm. and four palms makeone foot; six palms make one cubit; four cubits make once a man'sheight; four cubits make a pace, and twenty-four palms make a man'sheight..'[Klein, pg 68]
It would be nice to discuss measurement error and techniques,usage hints, historical notes on the units, averaging to createstandards, perhaps also calibrate precision/errorbars, ..
Angle
Gobdocuments 1 6 Cm =
See also Measuringangle & distance with your thumb.Icopybot 7 9 0. The visual height of your fist, held out in front of you, is about 10 degrees.
You can check this by starting with your arm straight out, and thanwalking you fists upward, hand over hand. At 9 fists, you should bepointed at the ceiling.
A brief elaboration: together, the distance from eye to outstretchedfist, and the height of the fist, form two sides of a right triangle,and thus determine an angle. (say 58 cm and 9 cm, 'opposite overadjacent' is 9/58, with arctan(9/58) = 9 degrees).
It would be nice to have some notes on usage, on sensitivityto fist distance, on measuring the distance to objects of known size(aircraft, people), on measuring the height of a building by walkingtowards it, on .. Ishowu studio 2 2 1 6.
References
The Science of Measurement : A Historical Survey / Herbert ArthurKlein. 1988 (Under another title in 1974). Especially pages 53-73.Comments/questions/thoughts encouraged. - [email protected].[Top][Musings]