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.
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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
I paid a little over $200 for this one. I was happy with that price.
I see you have a K scale.?ÿ That is x^3 typically.
The cursor also acts like a sort of memory register.?ÿ Say you did 2x4=8.?ÿ Say now you want to multiply 8 by 2.?ÿ You put your cursor over the 8 then run one of the 1 indexes to your cursor (either right or left which ever one doesn't run 2 off the scale).?ÿ Then you read 1.6 under 2, you have to know the answer is really 16.?ÿ You can go on back and forth like this until infinity.
8 is easy but if your intermediate answer falls between marks on the scale it starts to make sense that you would put your cursor over the answer then run your slip stick right or left again, nothing to remember or write down.
There is a way to know where the decimal point goes by how many times you move the "slip stick" part left or right.?ÿ I just can't remember what it is now.
There is a way to know where the decimal point goes by how many times you move the "slip stick" part left or right.?ÿ I just can't remember what it is now.
I computed the volume of a cylinder in cubic feet times 50 each divided by 27 for total cubic yards successfully. I considered that a major accomplishment.
There is a way to know where the decimal point goes by how many times you move the "slip stick" part left or right.?ÿ I just can't remember what it is now.
Yeah, there is a method, but I never thought it was worth keeping track of. I always just did crude mental approximations to set the decimal.
Funny how you guys seemed to think i was joking about "a slide rule for the old guy on the crew", yet here you are proving me correct.
All the current tech we use still can't replace an analog device for evaluating: multiplication, division, exponents, roots, logarithms, trigonometry, etc. (no batteries, etc.)
Funny how you guys seemed to think i was joking about "a slide rule for the old guy on the crew", yet here you are proving me correct.
All the current tech we use still can't replace an analog device for evaluating: multiplication, division, exponents, roots, logarithms, trigonometry, etc. (no batteries, etc.)
When I was in school thinking that I was going to be an electrical engineer we had a slide rule class. Our instructor, Fred Carden, looked and acted just like R. Lee Ermy. He had no training in how to teach, and ran the class like it was some form of Basic Training, which most of us did not respond to well. I will say that by the end of the class we knew how to use every scale on the slide rule to solve some sort of electrical engineering problem, although many of them we had not encountered yet. Still remember him 50 years later...
The eyes are glazing over on all participants under 60 at this moment.?ÿ Except for the math nerds who are treating the slip stick as some magic wand to amaze their friends...........both of them.
The eyes are glazing over on all participants under 60 at this moment.?ÿ Except for the math nerds who are treating the slip stick as some magic wand to amaze their friends...........both of them.
It's black magic I tell you this Automatic Proportion Stick.
Of course there is the 3 significant digit limitation, not very useful for most surveying problems.?ÿ I heard a rumor there were vernier models to gain a significant digit but I haven't seen one.
