I inherited my Dad??s Dietzgen slide rule 15 years ago. I??m trying to teach myself all of its capabilities. It??s like chess, the basics are easy to learn but it is challenging to become an expert. The device is ingenious really. It??s just a way to add logarithms together for multiplication and division but with various scales resized for other things like squaring numbers and so on.
Still have my Post Versalog from college. HP scientific calculator came out when I was a Sr but cost almost as much as a quarter room and meals in the dorm. I didn't get a calculator for some years, but had access to scientific desk calculator at work.
The other day I picked up Dietzgen equivalent to my slide rule at a sale for a buck. The cursor glass on one side is broken, but the other side looks cool in the display case with my great uncle's 20 inch slide rule.
Mike Segar... he was a union field surveyor on my crew back in 1977 +/- he truly mastered the slide rule. In those days almost every field calculation (even slope corrections) were made by every crew member, basic error checking. Mike zipped up the answer as fast, or Faster than the rest of us...amazing
the rest of us were using either a Curta or one of the new HP programmable calculators...
Mike was a long haired Hippy, lived in his VW micro-bus. I have no idea what happened to him later
=======
slide rules are awesome. I never became a wiz .... I still have a couple, not a clue how to use them now ========
Hoganmiller: he was the Geometry/Algebra/Calculus teacher at my high school. he had a Six Footer mounted on the wall above the blackboard. He used it in every lesson. in 1963-1968 we were all expected to become proficient with a slide rule
I had to buy a slide rule in the mid 1970s for high school chemistry class. I spent the first semester learning how to use it, then received a Bowmar Brain calculator for Christmas (my dad had done a survey for one of Bowmar's employees), and I never used it again.
I still have my slide rule and my dad's, as well as the Bowmar Brain in the display case in my office.
My dad kept using his into the 1990s, along with his Monroe mechanical calculator (which I also still have).
Nowadays, I would wouldn't dream of using such old devices. I use exclusively HP 11c calculators from the 1980s. I bought a lifetime supply of used ones on ebay about 15-20 years ago. None of them have failed.
I have an hp11c emulator on my personal iOS devices. I bought the genuine hp15c emulator for my new iPhone 13pro my employer issued me.
Using the slide rule I realize how lazy I??ve become about knowing the magnitude of the answer, just smashing keys on the calculator.
My slide rule is a Eugene Dietzgen Co. N1733 (polymath multiplex decimal trig type log log rule). I think mid 1950s.
I figured out how to work up the area of a circle which I considered a major accomplishment but I didn??t do it in a continuous sequence. Doing a series of calculations on a slide rule without writing down intermediate answers or even needing to remember them is what the serious power users can do.
It was one of the first available scientific calculators, if I recall correctly. I think I was the first in my class to have one.
It wasn't very reliable: I had to replace the keyboard at least once. It had an LED display and Nicad batteries. But it did have a full set of trig functions and a single register memory.
Checking my slide rules:
My 1975 Picket Model N902-T is in excellent condition.
Unfortunately, my dad's Picket & Eckel Model 500 with a copyright date of 1948 was an early model for them, and is made from magnesium instead of aluminum. It is badly corroded with a white powdery substance and though I can probably clean it up a bit for display, I'm afraid it will never slide again.
Here is a photo from www.sliderulemuseum.com/Pickett.htm
The NGS monument's old location is now occupied by a building.
So many things have changed. Slide rules, Cutra's, 8 place tables, 3 man crews, solars, I don't even think there are compass roses to layout anymore. Does anyone still do those?
I don't recognize the green instrument in the box.?ÿ It looks like it might be a Wild unit.?ÿ What is it?
I believe it's a Wild construction level of some type. It's got a long base, it rotates vertically with a vernier. I don't know how to use it, it was purchased at a garage sale.
I don't recognize the green instrument in the box.?ÿ It looks like it might be a Wild unit.?ÿ What is it?
It looks like an alidade for plane table topography.
you're probably correct, the base would need to rotate on the table, the telescope can sight and read stadia and there is a vertical vernier to turn to the rod.
I picked this teaching model a few years ago at a local antique store. I have no clue how it works but it looks cool in my office.
?ÿ
It??s pretty simple??the 1 is the index. The scale runs from 1 to 10. Say you want to multiply 2 x 4. You slide the middle 1 on C until it lines up with 2 on D below. Then you find 4 on C on read the answer 8 on D below.
You need to know where the decimal place goes. Most of the time 3 significant digits is the best you can do.
What you are doing is graphically adding logarithms because we know log(2)+log(4) = log(8). Notice that the distances between numbers get smaller as you move to the right.
A and B are for squares and square roots and CI is an inverse scale (runs right to left) for division.
You can use A and B together for simple multiplication and division or you can put your curser on a number on D and read the square on A, same with C and B. Square roots are done the opposite way.
That one is a simple beginner model, mine has log log scales for raising fractional powers and trig scales. I haven??t figured those out yet.
If you multiply something like 25.3 x 145 the answer you read is something like 367 or if you have really good eyes you might see 3668 or 3669. You would have to have an idea the magnitude of your answer to get about 3668 or 3670. So it??s an approximate answer. You would never get 3668.5 unless you had a really expensive specialty rule.
I'm pretty glad that I missed the age when those were common in math and engineering classes, and we all had basic TI calculators with trig functions by the time I was in middle & high school and college
