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See the "Illustrated Self-Guided Course On How To Use The Slide Rule" at
the International Slide Rule Museum:

https://www.sliderulemuseum.com/SR_Course.shtml

For navigation you may prefer trig scales graduated in degrees and
minutes instead of decimal degrees. K+E manufactured parallel versions
of their Log Log Duplex rule, identical except sexagesimal vs. decimal
degree trig scales. I think they were the only manufacturer to do that.

The "Mannheim" and "Rietz" rules with 9 and 10 scales respectively
almost always had sexagesimal trig scales. Their trig scales are on the
back of the slide, so you have to pull it out and flip it over. Some of
these rules have small windows with hairlines aligned to the left and
right D scale indices, so you can do readings and settings without
flipping the slide.

A disadvantage of the Mannheim rule is that scale S covers ca. 0.5° to
90. The corresponding sines have a range of two decades (0.01 to 1.0).
That means S is used in with A, also a 2-decade scale. On the other
hand, T covers a single decade so it's used with with D. If you're
working a formula which combines tangent and cosine (as in the Bygrave
method) this is exceedingly awkward.

The Rietz and most other well equipped rules have angles 5.5° to 90 on
S, and a separate small angle scale (usually labeled ST) which does
double duty for sines and tangents in the 0.5 to 5.5 range. Thus, all
trig scales cover one decade. For serious trig it's much nicer than the
Mannheim arrangement.

German rules generally put trig scales on the body. That works for many
things such as the classic textbook problem of measuring the height of a
tree, or even rectangular to polar coordinate conversion. However, I
don't see any easy way to form products of sines and cosines as in the
formula for great circle distance.

One source of unused slide rules is going away:

"We are currently in the process of liquidating all the inventory of
Sphere Research prior to closing the business, or selling the company in
its entirety.  Walter, the technical wizard behind its inception and
continued times, has passed away.  We are most grateful for all our
wonderful customers and if there is anything you need, want, desire, or
have a good home for, please let us know and we will send you a quote.
Sphere Research and Slide Rule Universe will remain in operation until
liquidation is complete. Thank you for your continued support.

"NOTE - BUSINESS CLOSING DEC 31:  Sphere Research's parts and test
equipment sales will end on December 31, 2024.  We have cherished the
opportunity to work with you.  If there is anything you would like from
our test equipment and parts inventory, please reach out (stock up now!)
and, if you'd like to book a shopping tour, we will open our doors to
you and encourage you to bring a large vehicle!"

There's no shopping cart system on their site. When you click the link
to buy an item, your email program creates a message to Susan at Sphere.
You have to fill in the item description by hand. The reply from Susan
will ask for your desired shipping method and billing information. (A
note at the site says she will be gone until mid-August due to health
problems.)

https://www.sphere.bc.ca/

--
Paul Hirose
sofajpl.com

   

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