[SI-LIST] Slide Rules. (Was Re: We ought to address mutual SI-EMI issues in this forum)
- From: Kim Helliwell <kimgh@xxxxxxxxx>
- To: Ken.Cantrell@xxxxxxxxxxx
- Date: Fri, 13 Sep 2002 08:47:23 -0700
On Friday, September 13, 2002, at 07:08 AM, Ken Cantrell wrote:
>
> Roy,
> Excellent summary and opinion, I'm sure all agree. I've got just one
> question:
> what is a slide rule?
Hmmmm, how old are you, sonny?
A slide rule was an archaic device, made of bamboo,
plastic, glass, and metal. It's what passed for a calculator
in my college days. Geeks (then known as "eggheads") of my
day wore them on their belts, much as they later
wore their calculator holsters.
Slide rules could not do addition; that was presumed
to be something a human could still do in those days.
But they could multiply, divide, take logs, do square and cube
roots, calculate trig functions and exponentials, etc.
Calculations were done by manipulating a center slide,
lining up marks ruled on the slide with marks on the
stationary portion; then lining up a transparent cursor
with a ruled line over other marks to read off the
results of a calculation. How the slide rule enabled
one to make such calculations is still something of a
mystery; results were seldom very accurate. Depending
on where on the scale your calculation was located,
you could achieve accuracies only of just over 2 decimal
places to (nearly) four places. But often the last place
was mostly a matter of squinting and guesswork.
Slide rules required no batteries or other "power"
source, other than the hands required to push the
slide and cursor around. There were no buttons
or displays required. In fact, it seems incomprehensible
that such a thing could ever have existed, let alone
been used for hundreds of years.
Today, sightings of slide rules are rare. They might
be found in museums, in the ruins of old aerospace
buildings, or forgotten at the bottom of a grizzled
old engineer's drawer. Slide rules once ruled, but
have been supplanted by battery powered electronic
calculators and spreadsheets. Technology marches
on....
Big :-), just in case!
>
> Ken
Kim Helliwell
Apple Computer
kimgh@xxxxxxxxx
408 974 9936
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