Who Invented Pi?

Date: 6 May 1995 22:40:04 -0400
From: Anonymous
Subject: Ask Dr. MAth

Who was the first person to use pi?
Linda Beyt
lbeyt@aol.com

Date: 7 May 1995 13:48:58 -0400
From: Dr. Ken
Subject: Re: Ask Dr. MAth

Hello there!

The concept of Pi is an extremely old one in mathematics, and we don't 
know who first figured it out.  It probably was discovered by ancient 
surveyors (after all, the word "geometry" means "the study of measuring 
the Earth") who noticed that round things were about 3 times as far 
around as they were wide.  There's a good book called "A History of Pi" 
by Petr Beckmann that you might look at if you're interested in knowing 
more.

The modern symbol for Pi (which I unfortunately don't have on this keyboard)
was first used in our modern sense in 1706 by William Jones.  He wrote:

    There are various other ways of finding the Lengths or Areas of 
    particular Curve Lines, or Planes, which may very much facilitate 
    the Practice; as for instance, in the Circle, the Diameter is to 
    the Circumference as 1 to 
    (16/5 - 4/239) - 1/3(16/5^3 - 4/239^3) + ... = 3.14159... = Pi.

I found this information in the book "A History of Mathematical Notation" 
by Florian Cajori.

-K