1920s Monroe Mechanical Calculator

A Monroe calculator, or adding machine, is one I've been seeking out since I got my Burroughs and Comptometer a few years ago. I had the chance to pick one up a few months ago and I have been really impressed with it!

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[TechTangents]

It looks like I missed that Monroe was acquired by Litton at some point but it's impressive none the less that they are still operating as a calculator company today!

[dangeary]

I used to service and repair these mechanical monstrosities.
Mostly mechanical cash registers, but a few of these.
Those things made working on cars look easy!

[kaitlyn__L]

I like how this also kind of serves as a mechanical, physical demonstration of what “computer architecture” actually even means.

The simplicity and usability definitely makes this win in my book. I also distinctly remember seeing those hand movements on the cranks in some older films.. hmmm.

Fascinating stuff. Love watching the numbers spin.

[gabrielpowers]

My Dad used to sell Monroe calculators back in the 50's-70's. I saw all the calculators and how they changed. I remember how amazed we were when dad brought home the first handheld calculator. You know they used to be really nice machines and some of them were very advanced.

[cemmy]

12:20 from what I understand, you would remove the lever when you left your desk so that nobody could come along and mess up your calculation. Kind of like removing the reverser handle from a locomotive so nobody can come along and take it out of neutral, or a lock-out padlock to prevent someone from turning an electrical breaker on when you're working on electrical equipment. Basically a "don't touch this" indicator.

[Monroe-systems]

Hello from Monroe! This is an awesome video that showcases one of our original calculators😎 We are happy to say that we are still going strong today and we actually just released a new printing calculator earlier this year! If there is any other super cool videos you have about our calculators we would love to see them!😀

[friiq]

7:39 I can see why you might think that your Monroe is a pinwheel calculator. The user interface works very similarly to that of a pinwheel calculator. However, all the resources I’ve read about Monroe machines say that they used a stepped drum mechanism. Pinwheel calculators use gears that have an adjustable number of teeth, but a stepped drum machine works by moving a cylinder with a staggered set of grooves on the side. There’s a good animation of it on the Wikipedia article for “Leibniz wheel”.

[mingshey]

Now I see why they say "grind the numbers". The crank gives you the similar experience to that with hand operated grain grinders. Thank you for sharing!

[JackNormalMemes]

The comptometer really was the manifestation of touch typing given physical form.

[wompastompa]

For me, it's doing long division by using 2 Addiator Arithmas. One for repeated subtraction, the other as a register.

[lobo]

Cool conversational pieces! Maybe if I happen to see one in an antique store I'll consider picking it up.

[daveboyt]

Thanks for posting this. I actually have one that I used (along with a slide rule) before electronic calculators came out. You explained a lot of features that I never figured out on my own, so it's coming down from the attic for another work session.

[nativetexan]

<My father, an insurance agent, had one of these on his desk still working as late as 1975. Electronic machines were already on the market, but the Monroe continued to do the work well, and was paid for. But, one could forget conversation with the customer when doing numbers. Children were not allowed near the machine, as even when skills for repair were still available, we were about 100 miles from any shop that would look at it. HIs mother, part owner, had one of the more modern Friden variety on her desk.

[fetus]

Holy crap these bring back memories . I had one like the newest you just snagged ... if it wasnt that one it was very close . It was in with a pile of junk in a box that i found as a kid, like just out of diapers .. it was something i would play with and most likely destroyed even further than it was when i found it . Hind Sight eh :S

[KenHargreaves]

Interesting stuff thanks. I really wanted to see what was happening with the division demo. Unfortunately with all the lights the digits were completely washed out. Sometimes I could get a glimpse, but mostly from my point of view on on a 55” 4K TV I would hear ‘and there you see the result’ and nothing had changed. No worries, the explanation was great and kept me watching to the end. Perhaps something to keep in mind when you do more.

[NeoNorse]

At a small-town thrift shop some years back I picked up a similar Monroe calculator. It is electrically powered (though it has a empty socket for a crank) and you can really smell the ozone when it runs! It was re-badged as a Vanguard product for some reason. I discovered that it was a Monroe calculator by the name stamped on the electrical cable. Some research done in the last few minutes suggests it is similar to the Monroe LAS-160 though the number keys alternate between white and black in groups of three so it is not a definite identification.

[Desmaad]

I'd love to get a Facit calculator. They're pinwheel calculators with a distinctive keyboard layout enabled by an internal carriage for the input register.

[solitairepilot]

Oh I found one of these at an antique shop like a year back. Just been sitting in my garage for a while since I fixed it

[wearwolf]

3.142 is rounded correctly so that's something.

[TheOriginalJGuns]

i resonate with the Monroe as I also spin all ways.