# Multical / Multator

Multical
Video
History and Models
Promotional material
Patents

## Multical

The Multical is a small adding machine that superficially looks like a pinwheel machine, but it actually uses an adapting segment mechanism. The design has been simplified in an ingenious manner without sacrificing too much functionality.

It has 10 input pins, while the carriage contains a single 15-digit main register. There is an 11th input pin that only has the values 0 or 1, and by setting it to 1 the top 5 digits of the register will be used as a counter so that you have a 10-digit register and a 5-digit counter. In this mode you do have to take care not to let the register overflow into the counter, as there is no way of suppressing the carry between them. The carriage has a clearing lever on the left which clears the register and counter.

When you turn the crank, the carriage tilts upwards to connect the main register to the actuating mechanism. This mechanism consists of toothed segments that rock forward to turn the register wheels, and which spring back when the carriage tilts forwards to disengage.

Unfortunately the mechanism only allows the crank to be turned in one direction, so subtraction has to be done with complementary digits. There is a switch to the right of the input pins which will, when set to subtraction mode, cause 1 to be added. This changes any nines complement setting of the input pins into a tens complement number. Unfortunately there is no way to avoid the overflow caused by the use of complements, so you simply have to use sufficient leading zeroes and ignore the overflow to the left. For example, if the register shows 1234 and you want to subtract 56, you would enter for example 00056 using the small numbers next to the input pins, set the switch to subtraction and turn the crank. This results in 1234+99943+1=101178. You have to ignore the leading 1, giving the answer 1178.

Incredibly, this calculator has back transfer functionality. You can turn the crank a small amount until you feel some resistance. This tilts the carriage, connecting it to the mechanism. If you then pull the clearing lever, the input pins will be moved by the amount being cleared from the register.

The serial number on the bottom is 44,897. The distributor, Eclair-Bureau of Paris, has given it a second serial number, 410,077.

I have another Multical in metallic hammer green enamel, but sadly it does not work properly. Some of the plastic number wheels have had the single left tooth broken off, and this causes those wheels to not transfer a carry, and to not be cleared by the clearing lever. Also the input display has broken on the tens input pin. I cannibalised some of its input lever tops for the other machine.

The serial number on the bottom is 32,311. The distributor, Eclair-Bureau of Paris, has given it a second serial number 405,495.

## History

In 1918 Otto Meuter designed some improvements on the troncet slide adder. He made a deal with Carl Kübler, who would found Addiator GmbH to manufacture these adders, and in return Otto would receive a fixed payment for each adder sold. Unfortunately inflation ran rampant in Germany, so within a few years this deal was almost worthless. Kübler refused to renegotiate the deal, and Otto Meuter decided to find a different business partner.

He went to Jean Bergmann, a calculator manufacturer. Bergmann made a version of the Comptator (a development of the Rapid Computer) with the name B.U.G. (Bergman Universal Gesellschaft). Otto Meuter developed and manufactured slide adders called the Pro Calculo, the Pocket Adding Machine and the Correntator. These were all then distributed and sold by Bergmann. In 1928 Otto Meuter founds the company Otto Meuter und Sohn, and begins to sell slide adders under the brand name Produx.

In the 1930s Otto Meuter tried to develop a printing calculator, but that was not a success. In 1940 he and Rudolf Martin came up with the ingeneous design for the Multator/Multical, a machine with few parts which could all be easily manufactured. It took a long time for this to get into production because of the war. Otto and Claus were both held captive by the Russians for a while, and when in 1948 the company was about to be confiscated by the state Claus managed to rescue most of the production equipment and bring them to the West. In 1950 Otto finally manages to join him there and together they rebuild the company.

In 1953 Otto Meuter und Sohn present the Produx Multator at an exhibition in Hannover, and the production takes off. It was sold under various names, and in several slightly different versions. Multical seems to be the name mostly used in France, because using the German pre-war name Produx would incur extra import tariffs.

Produx Multator I 1954-1956 812-7314 MulticalNo subtraction lever, short front
Produx Multator II1956-196613470-46000Multical, Multator RKSubtraction lever, long front with rotating knob
a×b×c calculator1963-197333834-(3)65300Summira XNo subtraction lever, long front with rotating knob
Produx Multator-4 1963-197353000-(4)63800Subtraction by turning crank anti-clockwise

At some point in the late 1960s the serial numbers were prefixed by a 3 or 4, depending on the model.

The Produx slide adders remained in production too until the 1970s. Here are some pictures of the Produx MA.

In 1958 Otto Meuter retires, leaving Claus Meuter to run the company on his own. Claus develops the Multator-4 to simplify subtraction and division. By 1973 production was halted due to the rise of cheap electronic calculators. Otto Meuter died in 1975.

## Promotional Material

Produx leaflet
1956?
Leaflet folded into four parts in one direction
75mm × 148mm

This is a leaflet for the Produx Multator (II). It has some examples of the calculations it could help with, and lists its advantages such as the size and weight and the back transfer.

Flyer for Multator 4 and a×b×c
1962
Flyer with postcard
211mm × 149mm

This is a flyer for the Multator 4 and a×b×c models. It has a perforation down the middle, and one half can be used as a postcard to order them. There is no copyright date, but a user review is quoted that says a machine bought in 1956 is still working now 6 years later.

## Patents

I have not found a granted patent for the Multator/Multical, but Otto Meuter and Rudolf Martin did file a US patent application on 8th July 1940. Due to the war with Germany this application was confiscated by the Office of the Alien Property Custodian before it could be granted, and presumably it was then abandoned. The application was made public, and could be found on archive.org and is also reproduced below.

Here are some other patents relating to Otto or Claus Meuter.

PatentFiling datePublish dateNameDescription
DE 367,59924-05-191923-01-1923Otto Meuter; Carl KüblerSlide Adder