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Meet the Felix Arithmometer

Hello! Connected Yandex Museum.

During the regime of social isolation, we, like many colleagues in museum matters, miss visitors:



Meet Felix, an arithmometer, one of the most popular exhibits in our museum. Few people manage to pass by and not try to figure out how it works. And I am Alexander Shmelev, an employee of the Museum. Under the cut, I’ll show you how our “Felix” is arranged, a few first arithmometers and many videos!

A bit of history


An arithmometer is a desktop (or portable) mechanical computing machine designed to perform precise multiplication and division, as well as addition and subtraction. The first mechanical calculating machines appeared in the XVII century:

- “counting clock” by William Schickard, 1623.

The mechanism consisted of asterisks and gears resembling a clock, hence the name. They worked with six-digit numbers and could perform all 4 operations. With sound notification: a call warned that the result of the calculations went beyond the technical capabilities of the device. Two manufactured specimens burned down, and the drawings were lost and found only in 1935.


A replica of the Shikkard arithmometer

- the summing machine of Blaise Pascal ("Pascalina"), 1642

Externally - a box with a lot of gears. Although the design made it possible to perform all 4 operations, it was convenient to work only with addition. It did not get wide distribution, but the principle of operation (connected gears) became the most popular for calculating machines of the next three centuries.


"Pascalina" at the Museum of Arts and Crafts in Paris

- Gottfried's arithmometer Wilhelm Leibniz, 1673

Leibniz invented to use a step drum - Leibniz wheel. Later it was included in the design of the popular Curta handheld arithmometer ("mathematical grenade"), which was produced from 1948 to 1970. How it looked:


Replica Leibniz arithmometer

And how it worked:


Leibniz Wheel Model The

direct ancestor of Felix can be considered an arithmometer invented by Wilgodt Theophil Odner, a Swedish-Russian mechanic and inventor. It was produced industrially in St. Petersburg from 1890 to 1918 and is known by the name of the author.


The Odner Arithmometer

The most important innovation in the design was the Odner wheel - a movable disk with levers and pins. When moving the levers, the pins leave their sockets, and the number of extended pins is determined by the position of the lever. The arithmometer allowed performing 4 operations: addition, subtraction, multiplication and division.


Odner Wheel

After the October Revolution of 1917, the heirs of Odner returned to Sweden and began to produce a computer under the brand name “Original-Odhner”. In 1924, the St. Petersburg plant was transported to Moscow, and the arithmometer became Felix.

The principle of operation on the video (carefully, English!):


“Felix” - in honor of Felix Dzerzhinsky


Under this name, several million copies were produced from 1929 to 1978. The production of “Felix” was carried out by the factories of calculating machines in Kursk (“Schetmash”), Penza (Penza plant of computer technology) and Moscow (Plant of counting and analytical machines named after VD Kalmykov (CAM)). By the way, SAM was also engaged in the production of electronic computers, such as Ural-1 , Strela and BESM-6 .

In the 70s, “Felix” cost about 10-15 rubles, and due to the fairly low price it was quite popular: electric calculators at the same time cost several times more. Arithmometers were taught to use even in schools. Feel yourself in the role of the operator of an arithmometer here: The link leads to the instruction manual.


Felix at YaTalks 2019

The photo shows a copy from the collection of Victor Boyev at YaTalks 2019. If you were in our museum until February of this year, then you saw this particular arithmometer. Everyone wanted to touch it (we think it’s all a matter of its inhuman charm), and we decided to get our own:



Controls for an arithmometer:

1 - a lamb for resetting the knob revolution counter;
2 - revolutions counter of the main handle 10;
3 - carriage shift handle;
4 and 7 - comma arrows, not connected with the mechanism of an arithmometer;
5 - valve for resetting to 0 positions of levers 8;
6 - result counter;
8 - drum levers, with which the value of the operand is set;
9 - lamb reset result counter;
10 - the main handle. On the case to the right of the levers 8 there is a hint on the desired direction of rotation of the main handle 10 during various arithmetic operations.

What is inside?


Our gray Felix was produced by the Schetmash plant in the city of Kursk - the corresponding logo is embossed on the case - the capital “C” in the frame. Made in the 70s, the last years of release - GOST 16346-70 is indicated. Dimensions: 320x155x135 mm. Weight: 3.5 kg.

I managed to get it in good condition: the handles rotated normally, the levers moved clearly, the counters did not jam. The only problem that has arisen is a tight carriage. So, disassemble and watch. I will share my experience: suddenly you are also lucky enough to dissect something like that.

To service the arithmometer, I prepared:

- a set of slotted screwdrivers;
- paper napkins;
- napkins made of non-woven material;
- machine oil;
- cotton buds;
- cylinder with compressed air;
- gasoline "Kalosha".



To remove the back cover, unscrew the 4 screws:



Remove the carriage covers:



Turn the arithmometer and unscrew 6 more screws:



Disconnect the part with the Odner wheels and the main handle:



1 - the Odner gear system; 2 - result counter; 3 - counter of revolutions of the main handle; 4 - an overflow call or a negative number in the result counter.

We unscrew the carriage latches and disconnect it:



At this stage there will be a lot of dust and other possibilities to get dirty - do not forget to prepare! We purge and wipe the insides. We lubricate the rubbing surfaces of the carriage with machine oil and you can collect everything in the reverse order.

Felix allows you to work with numbers up to 9 characters. There are other technical limitations: the results of addition, subtraction and multiplication should not exceed 13 characters, divisions - 8. When the result counter is full or a negative number is received, the bell rings: you must cancel the previous operation.

To prepare for work:

  1. Using the handle 3, move the carriage to the leftmost position.
  2. By rams 1 and 9, reset the speed and result counters.
  3. Latch 5 and turning the main handle 10 clockwise until it stops, reset the position of the levers 8 to zero.

To add and subtract numbers:

  1. Prepare the arithmometer for work.
  2. Set the first operand with levers 8.
  3. With one turn of the main handle 10 clockwise, add the first operand to the zero value of the result counter 6.
  4. Set the second operand with levers 8.
  5. To add, you need to turn the main handle clockwise one revolution. For subtraction - counterclockwise one revolution.
  6. Hooray! The result of adding or subtracting in the result counter. We remind you: if at the end of the turn of the main handle a bell rings, an overflow has occurred or a negative number has turned out. In any case, the main handle must be turned in the opposite direction.

Multiplication and division can be replaced by addition and subtraction. For more details, see the user manual, if you are not afraid, or here:


This is how the Odner wheel of our Felix works:


and result counter:


Felix is ​​not only charming, but also reliable. And I’m not only that the arithmometer has remained operational despite its venerable age. A large part of our exposition is a functioning retro technique. Once in a museum, electricity was turned off. But we were not taken aback: “Felix” and the office accounts did not disappoint!

After the pandemic, we will be glad to see you in the museum! We will learn how to use “Felix”, we will analyze it and show what is inside it. At the same time, try to divide by 0. In the meantime, I will be happy to answer your questions in the comments.

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