Do you know how to use one??

[John Stankus]

I...

Another piece of slide rule trivia - all the technical classrooms in colleges and many high schools had a huge teaching slide rule on the front wall above the blackboard.

...

JKJ

with apologies to Crocodile Dundee

That's not a slide rule, this is a slide rule.

I do have a five or six inch slide rule I hand to students who forget their calculator.

[Andrew Seemann]

35 or so years ago in school we used slide rules for a couple weeks as part of learning about logarithms. The math teacher handed them out a the beginning of class and collected them at the end. Only time I have ever used one. I did like the concept though; you get a better idea of the limitations of precision in a practical sense. One of my irritations in the analytical world is people who don't understand concept of significant figures.

[Lee DeRaud]

with apologies to Crocodile Dundee

That's not a slide rule, this is a slide rule.

The real problem with these is that there's no belt-loop on the case.
sliderule.jpg

[John K Jordan]

with apologies to Crocodile Dundee
That's not a slide rule, this is a slide rule.

Man, I'd drive half way across the country for one of those!
Somewhere I still have a working slide rule on a tie clip. The two would look great together.

As Andrew implied, one huge value of learning to do engineering calculations on the slide rule is it naturally helps you to understand significant figures. Teachers sigh at the student who divides three significant digits by two and writes down 10 digits from the calculator. And is 1200 two, three, or four significant figures? Another value is it forces you to think of magnitudes - does 1.51 really mean .00151 or 151 or 1.51x10^4 - what makes sense?

I keep these by my figurin' nest, mostly to enrich the education of young people when talking about math and science. One is a cheap plastic Pickett and the other is a high end K&E, double sided, precision slide, beautiful engraving, leather case - a wonderful machine.

slide_rules.jpg
Scales: K, A, B, T, S, ST, S, D, L, DF, CF, CIF, CI, C, LL1, LL2, LL3, LL01, LL02, LL03 and an extra D.
I can't remember what most of those scales are for and some I never even knew.

JKJ

[Andrew DiLorenzo]

I have one and can use it. I also have numerous TI calculators and have tutored on them to people just learning.

[Jim Allen]

I sold the 2 I had last year on eBay....

DSCN1137.jpg

[Ronald Blue]

That timing sounds off: the (normal-size) HP35 scientific calculator came out in 1972. (My senior year, '71-'72, HP gave beta-test units to everyone in the engineering school, and replaced them with production units at graduation.)

You are correct Lee.

Introduced on February 1 1972, the Hewlett-Packard HP-35 was the first handheld electronic calculator sold by HP, and the first handheld ever to perform logarithmic and trigonometric functions with one keystroke. In effect it was the world's first electronic slide rule. As opposed to later HP calculators, it has an x^y function, not y^x, and the trigonometric functions work in degrees only. It does not have a shift key like later models, but there is an ARC key for use with SIN, COS, and TAN to give their inverses. The story goes that it was made after William Hewlett was shown the HP9100 desktop calculator by his engineers, and asked for a version to fit in his shirt-pocket. At first, HP thought they would only make a few HP-35s for their own engineers, as no-one else would be interested. Then they decided to try selling it - and sold hundreds of thousands. The HP-35 is of special interest to collectors because it was the first HP handheld, and the world's first handheld calculator with transcendental functions, so I give more details of it than of other models.


Hewlett-Packard HP-35.

[Thomas Canfield]

Graduating with BSME in Jan'65, slide rules were the only game in town. No calculators and computers were only the key punch card main frame just coming into use, and not accessible. Of course, I had to also walk uphill both ways to/from all my 8:00 AM classes 6 days a week, for 4 years. That's right, 8:00 Saturday classes every semester.

[Bill McNiel]

Yes, I still have mine. Slide Rule was required in my High School math classes and essential for Structures Class (3 years) in Architectural School (no relevant HP calculators at that time). All I can currently do with it now is multiply and divide.

[Mark Blatter]

You are correct Lee.

Introduced on February 1 1972, the Hewlett-Packard HP-35 was the first handheld electronic calculator sold by HP, and the first handheld ever to perform logarithmic and trigonometric functions with one keystroke. In effect it was the world's first electronic slide rule. As opposed to later HP calculators, it has an x^y function, not y^x, and the trigonometric functions work in degrees only. It does not have a shift key like later models, but there is an ARC key for use with SIN, COS, and TAN to give their inverses. The story goes that it was made after William Hewlett was shown the HP9100 desktop calculator by his engineers, and asked for a version to fit in his shirt-pocket. At first, HP thought they would only make a few HP-35s for their own engineers, as no-one else would be interested. Then they decided to try selling it - and sold hundreds of thousands. The HP-35 is of special interest to collectors because it was the first HP handheld, and the world's first handheld calculator with transcendental functions, so I give more details of it than of other models.


Hewlett-Packard HP-35.

I used a slide rule a bit in jr high, then in high school, was able to afford an HP. I think it was an HP 45 and it cost me about $200. In jr high, all the cool kids carried around slide rules in their shirt pockets, or pants pocket and whip them out and use them. Then high school, you were so not cool if you had to use a slide rule. I loved the HP (RPN) and anyone that used a TI was made fun of because they weren't real engineering calculators.

That reminds me of my 9th grade science teacher. He had lost most of one thumb somehow but always made a point of still using it to count. He would count to five using his non-existent thumb and four fingers, holding up that hand. It always looked funny, saying five, but only holding up four. He did it to get kids to pay attention I think.

[Ole Anderson]

Both my dad's and my slide rule were K&E's. the bamboo ones with plastic faces. My first calculator was a TI30

Speaking of mainframes. the MSU computer center had a Control Data 3600. I spent a lot of time in 1966 perfecting and printing out basic trig tables, each page was one degree, rows were one minute, columns were 10 seconds. 90 pages per book. Wish I would have kept at least one page from each book. All data entry was on punch cards.

[John Stankus]

with apologies to Crocodile Dundee

That's not a slide rule, this is a slide rule.

I do have a five or six inch slide rule I hand to students who forget their calculator.

I’ll have to take a few close up pictures highlighting the woodworking in the large slide rule when I am back in the office Tuesday. I am guessing the wood is mahogany

John

[John Stankus]

Took me a little longer than I expected to take the photos.

IMG_0694.JPGIMG_0693.JPGIMG_0696.JPGIMG_0698.JPG

It looks to be made of mahogany. I didn't realize until I took the photos that there was an angle scale on the reverse of the slider.

John

[Roger Feeley]

I think I will teach my grandson to use a slide rule when he's old enough. I like the idea of touching your work. I still have and use a Vemco drafting machine. I guess that makes me old fashioned but there's something to be said for engaging other senses.

I hear that the SCUBA instructors aren't teaching the decompression tables anymore. They just hand you a dive computer and tell you to do what it says. Hmmmph. I don't carry the tables in my head and would certainly use a computer but I'm thinking that it would be hard to truly grasp how nitrogen builds up and outgasses without at least some passing experience.

By the same token, teaching logarithms with a slide rule seems like a great tactile experience.

[John K Jordan]

I hear that the SCUBA instructors aren't teaching the decompression tables anymore. They just hand you a dive computer and tell you to do what it says. Hmmmph. I don't carry the tables in my head and would certainly use a computer but I'm thinking that it would be hard to truly grasp how nitrogen builds up and outgasses without at least some passing experience.

Yikes, what happens when the thing breaks just when you need it? Sport divers shouldn't need decompression anyway, just follow the no-decompression depth/time limits. But always carry a table.

During my years of cave diving we had to make decompression stops after deep dives, sometimes more than one. In particular, one of our favorite dives require going to over 100' before the "real" dive even started. I can tell you it sure gets chilly waiting and incredibly boring at the stops, even in the "warm" Florida springs and even when wearing a good dry suit with an insulated layers. We got so bored there were practical jokes played.

JKJ