Basic slide rule theory and use (Part 5): Chaining and S/T/L scales

[@area46241]

Best slide rule tutor ever. Thanks Professor Herning!

[@738polarbear]

Great series on these wonderful instruments.

[@stevesmithing1552]

I enjoy your videos on slide rules. I have a Teledyne Post 44CA-600 (early 70s). I have a few K & E slide rules, but most of mine are Post slide rules. Keep up the great work on your slide rule videos.

[@ProfessorHerning]

Thanks Steve! After making all of these, I've thought of many ways they could be improved. This summer I may have some time to do updates.

[@Ensign_Cthulhu]

I'm glad I looked at this video series of yours. By a lucky chance, I have an Aristo slide rule that is DMS but otherwise identical to your little Hoffman. It is marked with the Mobil logo on the back, so I suspect it was the slide rule era equivalent of the office calculator, ordered in bulk and put out for Mobil employees.

[@ProfessorHerning]

I think that was a common thing on smaller slide rules like this. This slide rule is marked on the back with a hydraulic pump company name.

[@leo9463065]

When doing sine near 90 degrees or cosine close near 0 degrees, for example sin(82°) and cos(12°), for precision I usually use S scale with P scale since sin(x)^2+cos(x)^2=1. I find interest in slide rules in high school and later got a Faber-Castell 2/83N from a online shop with my friend (also interested in slide rule) for about 900 NTD (~30 USD). The manual is pretty much broken, but the case and the slide rule are still in good condictions. I learned how to use the A, B, C, D, CI, DI, K, S, ST, T and P scales from the library and online, after that I was able to do some calculations. This is fun to me, and it even saves me once when my calculator stop working during a test (yes, I did bring the slide rule when taking the test). Still learning about W scales, LL scales and some useful tricks.

[@ProfessorHerning]

Definitely the right use of the P scale! Where I am here in the US the P scale was very rare on slide rules. The W scales are quite interesting and not that hard to use -- if you haven't found it already, Faber-Castell's manual has a pretty good explanation of the markings on the rule that help you remember how to do basic multiplication/division with them.

[@АндрейДенисюк-ш7п]

0:57 Actually you could already read the answer on D under 2.8 on C. Correct? Same for 2:09. The answer is already on D under 2.3 on CI. Thanks for great tutorials!

[@Omnihil777]

7:00 My Graphoplex 620d Rietz scale has DMS (Minutes in this case) plus sometimes decimal in the trig scales, very peculiar IMO

[@ProfessorHerning]

Interesting! What do you mean by decimal in the trig scales then? I thought the 620d was totally DMS on the trig scales. I don't have one though. There is a Russian plastic slide rule I've seen with DMS on S and T but decimal trig on ST.

[@Omnihil777]

@@ProfessorHerning You got me there crawling through the collection, I got confused and it wasn't the Graphoplex 620d, that's, as you say, completely DMS! I was wrong, but somewhere I got one, still searching, maybe amongst the "nameless". I meant the division in tens, not in degree minute second, just wanted to make it short with "decimal", I meant " decimal degree division"

[@ProfessorHerning]

Maybe it's the same one I'm thinking about: www.sliderulemuseum.com/Soviet/S392_Soviet_LSLO_25-14P_1979.jpg

[@ianbcnp]

In the first example was there a reason that you didn't just put the cursor over 2.8 on the C scale and read off the final result - 5570 - on the D scale? Heading off to the CI scale at that point seemed to over complicate the calculation and reduce accuracy.

[@ProfessorHerning]

I made these videos when I was learning myself, and have been meaning to update them. I intended here to explain how to "chain" operations with the result on the D scale, not to get into the ways to do combined operations w/ C/D/CI.

[@ianbcnp]

Thanks for the reply prof. These videos are in a different league than anything else on youtube and have greatly improved my ability with the slide rule. Many thanks for your efforts and enthusiasm! Now I just need to improve my understanding of maths and trig to really be able to implement my slide rule abilities!

[@738polarbear]

It would be nice if you could post where to download manuals . I have tried ISRM ,Eric’s slide rules and Sphere Research but they are limited. Do you know a more comprehensive site as I have REALLY REALLY tried and failed?

[@ProfessorHerning]

I always end up Google searching. Like you, I haven't found a single source that's comprehensive.

[@738polarbear]

I think it would have been a good idea to quote the model number at the beginning of the rule you are using .

[@Omnihil777]

Love your videos. Got a little collection to, the American ones are not cheap to get in Germany ;)

[@ProfessorHerning]

Thanks! The German rules are tricky to find over here for a good price also.

[@erikwern144]

Interesting. I never used one of these standard rules in school. I did however when I was 10, learned to use the circular slide rule that my Uncle got a patent for. He received a patent in 1968 for his ABC circular slide rule which included decimal points. This "unfair" advantage led many school teachers banning its use in the classroom. BTW, I have a few of these slide rules in mint condition for sale

[@ProfessorHerning]

+Erik Wern -- I've never heard of the "ABC circular slide rule," although I have a KL-1 for demonstrations in class. Do you mean that the slide rule has some sort of mechanism for tracking the decimal point in the result? Share a link to a picture or description if there is one!

[@pinguluis7533]

I have a slide rule that can compute cosines without taking the compliment: The ARISTO scholar No. 0903.

[@ProfessorHerning]

Yes, many slide rules have complementary angles marked (often in red) on the S scale for computing cosine. This is also done on the T scale for cotangent.