The Darmstadt Slide Rule

[@jadenephrite]

Regarding 5:43, there is an alternate method to calculate 4^3.5 on the Darmstadt slide rule as follows: On the back side of the slide rule, move the slide to the left such that the 4 on the e^x scale is under the left index hairline. Flip over to the front side of the slide rule. Move the cursor to 3.5 on the D scale and read on the C scale that its number is 4.85. Next move the slide to the left such that 4.85 on the C scale is now over 1 on the D scale. Flip over to the back side and read under the left index hairline that the answer is 128. In summary, these operational steps performed: 4^3.5 = e^4.85 = 128.

[@jadenephrite]

Regarding 5:08, as an alternative to using the exponential scales while they are on the back side of the Darmstadt slide rule and having to flip it from back to front and back again. The slide itself can be reinserted to the front of the slide rule such that the exponential scales are now completely visible on the front. Doing so eliminates the need to flip the slide rule back to front and back again.

[@charlesmrader]

This is way off topic, but the videos about slide rules remind me of an incidence from my past. In 1956, I started college in an electrical engineering program. After the first night's homework, it was clear that I had a problem. It took hours to do all the needed arithmetic. The next morning, I asked some classmates about the homework and they all said it was trivial. They had all attended special science high schools and knew about slide rules. I had never heard of a slide rule. I obviously needed to buy one and learn how to use it. They all suggested a Kuffell and Esser log log decitrig, which cost about $75, which was way outside my means at the time. It was going to take me a few months to save up enough money for that. But there was available a cheap (75 cents) wooden slide rule, which I could easily afford, and which I bought. Kids can be cruel. I got a lot of teasing about my junky slide rule. One classmate was particularly persistent. After a few weeks of it, I had had enough. So I said to him, "I can get more accuracy from my slide rule than you can get from yours. Let's have a contest." Another classmate would give us randomly chosen 3 digit numbers ( from a telephone directory). My tormenter was to use his slide rule and give as accurate an answer as he could, usually to 4 decimal places, sometimes only three. I would then give my answer, which was always one or sometimes two decimal places more accurate than his. After a few rounds of this, he never figured out how I could possible be getting more accurate answers from my obviously inferior slide rule. What I was doing was using the slide rule to multiply two digit numbers, the two least significant digits of the random numbers, then getting the last two digit of the product my multiplying the training least significant digits in my head, reducing the product modulo 10, and finally stitching the last three significant digits into the three most significant digits of his answer. He never figured it out, but he never teased me again.

[@jkneathery]

A great trick to fool a slide rule bully! LOL

[@miszcz310]

Just a small comment. Koroliev and von Brown used nestler 37 electro. A bit different than dramstad. Nestler wooden slide rule are still very nice to use because they are made from Mahony wood which was cut in early, mid XIX century. So it is pretty well seasoned and therefore stable.

[@MrShobar]

I won that Deci-Lon in a high school science contest in the very early 1970's. I used it in college. Majored in Mechanical Engineering.

[@samanthabloggins1775]

Our daughter just picked up a sliderule at ValueVillage this week!! She had no idea what it was! When she brought it home hubby showed her how to use it as i had forgotten how!!

[@martinfiedler4317]

WOW. Think, this is the model that my great-uncle used when he was an engineer. "Inherited" it as a child, but never learned to use it.

[@ganymedkallisto5561]

Darmstadt Sliderules are my favorites. By the way: You could also turn the slide-strip around when calculatong 4^3 for better readabity. Greetings from Germany

[@urugulu1656]

if it were for 4^3 he could just read the very top scale with the cursor at the 4 in the d scale. but since he is doing 4^3.5 this is not accurate.

[@urugulu1656]

btw it can also convert PS (essentially horsepower) to kilowatts and diameter to crossectional area. so if you ask if that 0.5mm in diameter wire is the 2mm^2 wire you are looking for it can do that on a dedicated scale

[@gustafbrackman3027]

This Nestler is probably older then 1950s as "D.R.Patent", Deutches Reich Patent (German State Patent), sign, visible in the well was used between 1919 and 1945. I would say that this slipstic is not older then 1930s, I think that they used different typeface before 1930. Anyway Nestler rules are very good, precisely manufactured and quite pretty. I have similarly dated No23R - rietz system "poor brother" of No21 and calculating with it is really satisfying.

[@jkneathery]

Thanks for the comment and info Gustaf. The really old 21 slide rules have a thicker metal cursor than this one. Perhaps this one is from the early to mid 1940s. This SR still operates smoothly and the numbers are still bright. The use of 3 colors and the "railroad" tick marks make this model easy on the eyes.

[@gustafbrackman3027]

I overlooked the cursor frame while estimating production date, now I checked it in the catalogue and you are right, thanks for highlighting that.

[@sry525]

i have one of these but its missing the cursor for the angles sad i wont be able to use it for that

[@SuperCat]

Greetings from Ireland, I have this model slide rule and I love it...

[@jkneathery]

Thanks for viewing SuperCat. I dream of visiting Ireland someday as many of my ancestors came from there.

[@marklammas2465]

"Pint of Guinness please, and I'll have one of those slide rules while you're about it"...

[@matthewfarmer2520]

That slide rule it's made out of Bamboo, very cool. I'm glade you got one. thanks for sharing.👍

[@cancersean]

Bamboo is used because natural oils in it make it self-lubricating. You are warned NOT to use any type of lubricant. Just slide it back and forth a number of times if it’s sliding a bit tight

[@prof.dr.abronsius8939]

I have a 'pi' on the logscale itself, and an 'e'; but what does 'c' mean??

[@jkneathery]

On some sliderules, the c is a constant = 4/pi or sometimes sqrt(4)/pi. A constant that is common in solving geometry problems related to Diameter and circumference of a circle. Not terribly useful imo.

[@DevilSpider_]

I have the same exact slide rule at home.

[@jamesHadden-l6l]

Have the 23/R

[@riadriddick1680]

AVENDRE: J'ai 140 règles de calcul tout neuf N°57/88-Reitz-N-Etudiant & N°57/89-ETUDIANT LOG LOG.Fabrication allemagne en 1965.

[@your-mom-irl]

je veux manger le poulet avec de la mayonaise

[@tkarlmann]

I would NEVER buy any slide rule with 'conversions' on the back made before 1960! Do you know why? 1960 was IGY == International Geophysical Year. Example: 1" now == 2.54 cm EXACTLY; not so before 1960 -- before then that, conversion was some other number. How IGY might creep into calculations, I'm not certain -- but I would not trust them!