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Date: Fri, 29 Sep 2006 13:01:02 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Fuel-Weights and Measures
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M Roberts wrote:

> I never really appreciated the English system of measure until I 
> started doing a lot of construction. In this instance, the English 
> system is a very logical and useful way to do things. You can use 
> fractions without a calculator. The real strength however is the use 
> of 3-4-5 triangles for squaring large structures. Also for calculating 
> rise and run of different roof pitches. My guess is the base 12 system 
> has it's origins in the guilds and cathedral builders of old.
>  

Nawh, it goes back a little further than that.  
http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Babylonian_numerals.html

And if you could imagine trying to build such structures without a tape 
measure.  You could notch a stick to get a consistent inch, but long 
stretches would best be measured with flags or knots on a string.  Very 
easy to double the string to find the middle, then double it again to 
get a fourth.  Somewhat more difficult to get tenths.

-- 
         ,|"|"|,              Ernest Christley       |
----===<{{(oQo)}}>===----    Dyke Delta Builder      |
        o|  d  |o        http://ernest.isa-geek.org  |