**Electro-mechanical Counting Devices**

These are counting devices that could be operated both electrically and mechanically. Electro-mechanical devices include the following:

- Speeding Clock
- Blaise Pascal machine
- Gottfried Leibniz Machine

**SPEEDING CLOCK OR CALCULATING CLOCK**

In 1623 and 1624, reported his design and construction of what he referred to as an arithmetical instrument that he has invented but which would later be described as a (calculating clock). The machine was designed to assist in all the four basic functions of arithmetic (addition, subtraction, multiplication and division). Amongst its uses, Schickard suggested it would help in the laborious task of calculating astronomical tables.

**The machine could add and subtract six-digit numbers, and indicated an overflow of this capacity by ringing a bell. **The adding machine in the base was primarily provided to assist in the difficult task of adding or multiplying two multi-digit numbers. To this end an ingenious arrangement of rotatable Napier’s bones were mounted on it. It even had an additional “memory **register**” to record intermediate calculations. Schickard’s machine was not programmable.

**BLAISE PASCAL’S CALCULATING MACHINE (Pascaline)**

Blaise Pascal was a French man who invented the first true adding machine in 1642. He was a mathematician as well as a philosopher. In 1642, he began working on calculating machines and after 3 years invented the mechanical calculator called Pascaline.

Blaise Pascal was born in France in 1623 and died in Paris in 1662. His machine was based on Abacus principle. The machine was built to assist his father to perform tedious tax accounting (auditing of government tax accounts). The machine was invented when he was 19 years old. **He designed the Pascaline to add and subtract two numbers directly and to perform multiplication and division through repeated addition and subtraction.**

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**STEPPED RECKONER**

This machine was invented by Gottfried William Von Leibnitz. He carried out further development on the work of Blaise Pascal so that multiplication and division could be possible directly. He invented a machine called “THE STEPPED RECKONER” in 1694. The machine is a mechanical calculator which can do multiplication, division and calculate square roots. The process of multiplication involved repeated addition. It was the first calculator that could perform all four arithmetic operations (addition, subtraction, multiplication and division).

**EVALUATION**

- Mention four electro-mechanical counting devices.
- Who invented the Stepped Reckoner and what year?
- When was Blaise Pascal’s adding machine invented?
- The design of Pascaline was based on which principle?
- The machine was built to assist his father to perform …………..

**See also**

MECHANICAL COUNTING AND CALCULATING DEVICES

HISTORICAL DEVELOPMENT OF COMPUTERS

MODERN METHODS OF TRANSMITTING INFORMATION