Arithmometer

History

The Odhner was invented in 1874 by Swedish engineer W. T. Odhner.

The Odhner machine was a rotary, crank-operated mechanical calculator based on the pinwheel principle. His successful design became the model for many other successful calculators which followed, such as the Friden, Brunsviga, and Marchant.

He first produced the Odhner Model 1 Arithmometer around 1886. He obtained a patent on his machine in 1891.

It was later mass produced in St. Petersburg, Russia. In 1926, it sold for about $300.

Addition:

Set dial to first number.
Turn dial toward "+".
Set dial to second number.
Turn dial toward "+".

Subtraction:

Set dial to larger of two numbers.
Turn dial toward ":".
Set dial to second number.
Turn dial toward ":".

Multiplication:

Set dial to larger of two numbers.
For each digit of the second number you will turn the dial that number of times toward "+" for the position of that digit on the left counter.

For example: If we are multiplying 768 x 256 then:

a) turn the dial 6 times;

b) shift the left counter right;

c) turn the dial 5 times;

d) shift the counter right;

e) turn the dial 2 times.

The result will be shown in the accumulator, which in the counter you should see the second operand (in this example: 256).

Division:

Move the left counter all the way to the right.
Set the larger of the two numbers starting from position 6.
Turn the dial once toward "+" to enter the dividend into the accumulator.
Zero out the counter.
Now enter the divisor again starting at position 6.
Turn dial toward ":" until a ding. On a ding always undo the last calculation by turning the dial toward "+".
Shift counter left.
Repeat 6 and 7 for each digit until done. You can keep going to beyond the zero position, in which case place the pointer on the counter in a position to indicate the separation point for decimals.