I’ve just bought a pretty complete set of De Kantoormachine Gids (Office Machine Guide). In the 1940s/50s you could subscribe to get sent updates with all the latest office machine releases. There are 12 ring binders full, but of course I’m mostly here for the 2 or 3 about mechanical calculators

Yesterday’s flea market had this nice Comptometer model H. Nice to see a tag with lots of info on it. I like to think the seller used my site to help with that.

I just added to my site this manual for the Thales GEO double-register mechanical calculator, and uploaded a scan to archive .org. archive.org/details/thal... This was a special model with two input registers and two accumulator registers, attached to a single crank. I don't have this model, but...

I wanted to display my Dad’s Curta, and it kind of got away from me.

At today’s flea market I only saw this little Resulta E7, a small adding machine from Germany. This version is from the 1960s, though the first versions were made in the 1930s.

So here is the Locke Adder. A gorgeous looking thing which is really no more than an abacus. It does not even have a carry mechanism. I spent a lot of time looking through digital archives to find out more about it and the maker, Clarence Elmer Locke. I found a few things that seem to be new. 1/3

Jaap Scherphuis@jaapsch.net · last mo.

Today I learned that baby jumpers were invented way earlier than I ever thought. The following newspaper ad is from January 1906. I found this during my research into the latest addition to my calculator collection. I'm sure you can figure out what it is. The second ad is by the same company.

At today’s fleamarket i saw just one mechanical calculator, a Contex-10 in its carrying case. Made in Denmark, 1957-1971. These machines were cleverly designed to be as cheap to make as possible while still providing a lot of functionality, so they became very popular. In the US sold as Bohn Contex.

A year or two ago there was a 3D-printed Curta mechanical calculator, but that had to be made at a much larger scale for the tiny parts to be printed accurately enough to make it work. Last week a video appeared with a stepped drum design adapted to fit in your pocket. Amazing! youtu.be/WQeWL3TyeQQ

I Fully 3D Printed a Mechanical Calculator

YouTube video by 3D all Workshop

youtu.be

Today I learned that baby jumpers were invented way earlier than I ever thought. The following newspaper ad is from January 1906. I found this during my research into the latest addition to my calculator collection. I'm sure you can figure out what it is. The second ad is by the same company.

I saw no mechanical calculators at today's flea markets, so instead I'll show you the Olympia 1182-030 adding machine that I added to my website yesterday. It is a pretty standard manual adding machine, but it is nice how the rear hinges open for replacing the two-colour ribbon. jaapsch.net/mechcalc

On today’s visit to the fleamarkets I saw just one mechanical calculator, a good-looking Triumphator CRN2 pinwheel machine. These were made in Leipzig, East Germany, from about 1958 to about 1964.

I didn’t see any old mechanical calculators at the fleamarket yesterday, but I did see one adding machine last week while I was on holiday. I didn’t buy it, as this Olympia was not special enough to lug all the way back from Tenerife.

Some pictures of the partial solar eclipse. I used a stack of old photo negatives as a filter on the first one, and a CD on the second one. #SolarEclipse2026

On this weekend’s stroll through the fleamarkets I saw only another Plus Adder. Not the same one as last week though, as it has 6 input columns.

Went to the fleamarkets today as usual on Sunday, but there was not much of interest. I only saw a Solo (a small plastic adder with coaxial input wheels) and an older Plus adder, shown below. Still, nice to be out and about in this weather.

A local second hand shop has some antique sewing machines, of various brands. This one caught my eye because I recognised the name Naumann. It was made by Seidel & Naumann who also made some adding machines. I have one of those adders of course.

Here is a video of the Add-O-Matic from 1947. I found out some new info from looking through online archives. Behind the sales company was the manufacturer United Enterprises Inc from Chicago. They made stainless steel cutlery, but also some other surprising things. (1/3) youtu.be/Uhhk94cbZ0A

The Add-O-Matic adding machine (1947-1949)

YouTube video by Jaap Scherphuis

youtu.be

Before Turing Machines, computability theory, and computational complexity theory, there were computers. They were people: mostly women. This is one of my favorite photos of a computer, because it shows her using two distinct computing methods.

There was an inventor named William T Phillips who in 1917 developed an mechanical calculator. Just before he died in 1937, he wrote a biography of Butch Cassidy. Phillips had confided in friends that he had an outlaw past, and the unpublished manuscript had details that led some to believe ...(1/3)

Here is a peek into how newspapers used to be made. I have a newspaper photo from about 1918, showing one Genevieve Deasy who was the world record holder on doing calculations on the Comptometer mechanical calculator. They inked the background black, and used white to accentuate some lines. (1/2)

Burroughs were always trying to one-up Felt and Tarrant, the makers of the Comptometer. Felt and Tarrant printed The Soldiers' French Phrase Book, giving it to soldiers for free. In the back is a Comptometer ad calling it the "Rapid-Fire Adding Machine", and the "Machine Gun of the Office".

Debbie Cameron@debsadelight.bsky.social · 5mo ago

truly bizarre advert from the telegraph in 1916. It's for an adding machine- love the old fashioned quill pen though! #Ww1 #WomensWork

Since Inflatable Children's Play Structure Discourse seems to be occurring on this hecksite, I wish to note that I still have not received my free inflatable slide rule.

AI slop is ruining everything. Just look at these impossible monstrosities...

Inventions That Shape Our World@inventionsarchive.bsky.social · 5mo ago

Mechanical calculator (Arithmometer) Core identification details for the Arithmometer mechanical calculator. Invention Name Mechanical calculator, specifically the Arithmometer Short Definition A hand-operated calculating machine designed to perform the four basic arithmetic operations through a…

Saw this gorgeous Britannic mechanical calculator at a fleamarket this morning. If I didn’t already have one, I’d have snapped it up.

My latest video shows the Little Giant Adding Machine, made in the 1940s by Kel-San in Dayton, Ohio. www.youtube.com/watch?v=NrR0...

Little Giant Adding Machine

YouTube video by Jaap Scherphuis

youtube.com

Soooo satisfying!

I think this is the oldest thing in my calculator collection - a Stephenson adder. On the back it says Beardstown Illinois, and an 1873 patent date. Stephenson moved to Wilmington in around 1879, so that makes it about 150 years old. I do wonder what kind of person first bought it back then

I think one of these books would benefit from a different font.

I just posted a video of the Vaucanson AVA13 mechanical calculator. You don’t see these very often outside France. This one was used in the 1950s by the Dutch Royal Army at the barracks in Schoonhoven (havenkazerne). (1/2) youtu.be/16-o-QOOnvE

Vaucanson AVA13 mechanical calculator

YouTube video by Jaap Scherphuis

youtu.be

Finally made a video if this machine. It seems to be quite rare since I have not found any trace of it on the internet, no mentions at all, let alone pictures. The only info is the patents. Schildkröt Minirechner 99 youtu.be/3su3Y6Kmzp8

Schildkröt Minirechner 99

YouTube video by Jaap Scherphuis

youtu.be

Jaap Scherphuis@jaapsch.net · last yr.

Recently I bought this toy calculator from 1971. It is quite clever how its 2-digit register is shown not just as digits but also with columns of coloured dots.