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Researches

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I cannot figure out what I’m doing wrong.

2 X 3 = 6

Came with a very nice leather case.

I GOT IT!!

Kinda sorta.

Oh. For you youngins, it’s called a slide rule. It’s how we did math– all math– before the invention of the handheld calculator.

Also in the mail today, Thomas Jefferson’s Garden Book 1766-1826.

Carry on!

14 Responses

    1. I’m probably going to abandon the crappy old books and hit YouTube for some instruction. I can do some multiplication and get it right, but for some reason, not all. Haven’t even tackled anything more complicated.

      Stay well!

  2. What you are showing is 12 X 13 = 156…or 1.2 X 1.3 = 1.56. The 2 is to the right of the plastic cursor.

    More formally it is 1.2 times 10 to “some power” times 1.3 times 10 “to some power”. The answer is 1.56 times 10 to “the sum of the two powers”.

    2. YOU’RE AN ENGINEER?!? This is fantastic! Would you mind if I asked a question or two? Nothing complicated.

      2. Thanks! From the perspective of a beaver (second only to man in his ability to shape the environment to suit himself) building a 2-3 story lodge on the bank of a lake, what would be the “tools” he would need to do calculations regarding rates & force of water flow, viscosity of mud at given temps, strength of the walls, etc. Importantly, the tools should be those used before the advent of the handheld calculator. So like in the ’50s.

        It’s a talking beaver, of course.

        Now that I think of it, what I’m asking is what instruments would an engineer have used back in the day to measure the various things which need to be measured to construct a beaver lodge, many of which last for years.

        Thanks!

      3. I’m an electrical engineer, but I do like to study how “things were done in the old days”.

        To do the actual calculations, pencil, paper, the slide rule and if needed for more precise answers, a book of math tables.

        A flow cone and a watch can be used to measure viscosity. A man named Marsh came up with a standardized version in 1931, but I’m sure the principle had been around a long time before that.

        The tape measure, ruler and measuring chain are good for length measurements. They have been around for a very long time.

        The carpenter’s square comes in handy for doing things with roof pitches (and cutting stair stringers (the part the steps sit on) as well being used as a ruler. This, too has been around a very long time.

        The protractor for measuring angles without having to keep diving into the trigonometry stuff on the slide rules or in the books, has been around awhile too.

        Measuring force can be done with a spring scale. As far as I know, the spring scale is probably 300 years old. The scale itself can be calibrated by attaching attaching known weights to the spring and measuring how much the spring compresses or stretches.

        I’m going to go out on a limb (sorry for the pun) and say that I’ve seen a lot of “didn’t survive” beaver dams that were not destroyed by humans, so my guess is that the beaver dams that did survive were probably very “overengineered” by the beaver.

      4. This is truly awesome. Thank you so much for taking the time. We have a beaver lodge on our lake. In the spring we set up the trail cam to watch them. Your “overengineered” comment is well-taken.

        Re: done in the olden days. One unintended consequence of the digital world is that folks have lost their pattern detectors. I showed my trig sliderule to a young woman who’s very smart and slid some things around to show her how it worked functionally. I handed it to her and asked what she saw. No clue. At the very least, and without knowing a thing about the underlying mathematics, I see power transformations. How can you not?

        Thanks, again. Your mention of math tables was great. Turns out I have “Cameron Hydraulic Data” which has a chapter on Water Data!

      5. I very much enjoy learning engineering history and the “this is how it was done in the old days”.

        Often it allows me to, “Well, if we combine this tool with that meter and do a little math, we can make the measurement in half an hour. Yes, I know the correct device will give instant results, but we only need to do this once and the correct device won’t be here until tomorrow morning.”

        The old ways often involved more use of professional judgement (fancy name for ‘rules of thumb’) and less calculations…such that some judgement and quick mental math will give an acceptably close answer.

        It’s fun to have someone ask an almost rhetorical question and, in 2 seconds, “Oh, it’ll be just a tiny bit more than 4.8” and then walk away…and…they go work the calculator for several minutes and come up with 4.802.

        It let the “kids” know that I wasn’t senile! 🙂

        More seriously, it gives some confidence that the calculations were done correctly.

      6. So I take it they give you the same look as I get when I give a cashier $2.02 for something that costs $1.77?

        We have a friend who used to head the Anatomy & Neuroscience Dep’t at the medical school in Jackson. The dep’t was moving into new digs and dismantling the old conference room and getting rid of its library. I asked Mike if I could buy some of the old books. “Take anything you want.” Whoa boy!

        You would think medical school type books, right? The vast majority were handbooks of the old fashioned variety. Metals. Radio Engineering. Electrical Engineers. Merek. Etc. So those guys built a lot of their own experimental equipment. And then fixed it when it broke. Seat of the pants.

        Mental math. Making change. Thumbs up.

      9. Thanks! Some rain but we got more from the front that moved through yesterday morning.

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