[AT] OT pocket knives

[Recentjester at aol.com]

just what I need to get my bearings (pun) 
 
 
In a message dated 7/14/2015 6:23:16 P.M. Central Daylight Time,  
charliehill at embarqmail.com writes:

I'll see  if I can find it.  I was trying to remember from almost 50
years ago  something we were taught in Engineering Graphics.
I can't remember the  details but there was a curve (sine curve or whatever)
drawn above the line  on a drawing sheet and somehow using drafting 
instruments
we  transferred measurements from the curve to the area below the line
forming  another shape (maybe a straight line?) that represented the 1st 
derivative  of
the curve.   Does that sound at all right?   I just  can't remember the 
details.  I remember
at the time being somewhat  amazed at the process because of it's 
simplicity 
and  result.

Charlie


-----Original Message----- 
From:  rlgoss at twc.com
Sent: Tuesday, July 14, 2015 6:33 PM
To: Antique tractor  email discussion group
Subject: Re: [AT] OT pocket knives

BINGO! I  found an article on-line about this planimeter, folks.  It even 
has  
a
name -- Prytz or Hatchet planimeter.  for a good discussion  (complete with
illustrations, formulas, etc.) search for make-shift  planimeter, and go to 
the
PDF written by professors from Wabash and  Western Connecticut --Area 
Without
Integration: Make Your Own  Planimeter.  After reading this article, I 
remember
having made  one of these out of a straightened clothes  hanger.


Larry
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