[Woodcarver] Geometry question for the group

[Classic Carving Patterns]

Bill, you made me smile, Thank You!
 
This fun math problem has had Mike and I discussing geometry  which lead
to discussing units of measurement which lead to the following somewhat
related thought!  (See the light bulb going off over my head.)
 
Back in art school I was taught the 'traveler's ruler' theory which is:
1.  The width of the first and second finger held together is approx.
one inch.
2.  The length of the hand from the wrist joint to the tip of the middle
finger, when the hand is flat, is approx. 6".
3.  The length of the foot, which is equal to the distance between the
wrist joint and the elbow joint is approx. 1 foot.
3.  The length of the arm from the elbow to the tip of the middle finger
is approx. 18", which also happens to be the approx. measurement of a
man's stride, also called a cubit.
5.  The distance from the tip of the nose to the tip of thumb, with the
arm parallel to the shoulders, thumb pointing forward, is approx. 36" or
1 yard.
 
As this simple theory was set back when the average man stood about 5'
tall the measurements are a touch off today, but still reliable enough
for quick use. And if you know the real measurement for the width of the
first and second finger that ratio can be applied to your 'traveler's
ruler' measurement to create a fairly accurate measurement.  Example: if
your "two finger" measurement is 1.25 inches and you have a three  "two
finger wide" board you multiply 3 x 1.25 for you finished number of
inches.  So your board really is about 3.75", the true width of a
standard 2x4.  You will be pretty darn close.  Plus it is the main
reason I will never be able to think freely in the metric system  ... my
ruler no longer works!!!!
 
Oh, and the first compass was discovered when a carpenter firmly put his
elbow on some board, held his pencil (probably it was really a piece of
charcoal from his hearth) and swung his hand using the elbow as his
anchor point.
 
Just thinking out loud.
 
Susan
 
Carving Patterns Online
Designs Online Since 1997!
Classic Carving Patterns By L.S.Irish
http://www.CarvingPatterns.com
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-----Original Message-----
From: Bill Judt [mailto:bjudt at sasktel.net] 
Sent: Thursday, September 30, 2004 12:45 PM
To: [Woodcarver]; irish at carvingpatterns.com
Subject: Re: [Woodcarver] Geometry question for the group


Susan:

Such a practical and simple approach to this otherwise complicated
geometrical problem.
I am impressed. Most competent computer graphics programs will draw a
circle to a specified circumference.
Are there other ways to draw a circle to a specified circumference using
compass and ruler?

Thanks

Bill
List Owner

W.F. Judt,
46 Harvard Cres,
Saskatoon, Saskatchewan,
S7H3R1
PH: 306-373-6649
Email: bjudt at sasktel.net
Website: http://www.wwwoodcarver.com

On Sep 30, 2004, at 7:04 AM, Classic Carving Patterns wrote:


It's been a very long time since I have had to do any geometry equations
... But as I remember a prime number is defined as being evenly
divisible only by 1 and by itself; 13 divided by 1 = 13 and 13 divided
by 13 = 1. So what I would do is first create a circle that has a 13"
circumference. Therefore you have a point every one inch along the
outer circumference line and you have a center point to create the
radius lines. Those lines will be true then for any sized circle that
you need, you only need to extend them to the new outer edge of the
larger circle.

Susan