When I was a motorcycle mechanic I had a circular slide rule, with a
permanent mark at the coefficient for computing a catenoid, as I did a
lot of 2-stroke exhaust systems. Some hilariously wrong, some which got
me a reputation as a wizard.

--dave

On 6/1/23 18:08, D. Hugh Redelmeier via talk wrote:
| From: Scott Allen via talk <[email protected]>

| I thought the circular ones were an interesting idea but I only had a
| cheap plastic straight one.
| https://www.sliderule.tokyo/products/detail.php?product_id=8

Yeah, I had a cheap one from Coles Book Store discount bin.

With a regular slide rule, you had to realize when to wrap around:
5 x 5 would go off the right end so you had to go left to 2.5 (and
to increment the in your head expoent).  With the circular slide rule, the
wrapping was automatic but you still had to increment the exponent.

One of our classrooms had a very large demo slide rule.  7'?  It was
yellow so I think that it was a Pickett
<https://dannychesnut.com/SlideRule/SlideRule.htm>
That should have given 4 digits of accuracy

A colleague in the Computing Centre at Waterloo showed me a helical slide
rule.  It must have been something like this:
http://retrocalculators.com/otis-king.htm
The result is an extra digit of accuracy without being too large

| The year after I learned "slide rule" in high school, training was
| dropped because calculators were becoming the norm.

Every new techology begets grumbles about what was lost.

- analogue leads to elegant, precise, timeless devices

- a slide rule forces you to have a feel for the answer.  At a minimum,
   the power of 10.

- a 10-digit answer from a calculator makes you think you have the 10
   digit answer.  Almost nothing you measure (as opposed to count) has that
   much accuracy.

Me?  I like discrete problems.  Perect for digital computers.  I have
calculated precise and accurate numbers that are thousands of digits long.

Of course some have calculated millions of digits of the decimal
representation of Pi.  Not with a slide rule.
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David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
[email protected] |              -- Mark Twain


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