Mechanical Computing device

(i) Napier bones:

In 1964  John Napier invented logarithms and a device called Napier bones or rods.This device helped to multiply numbers and do various types of simple calculations.

This device is used for calculations  of products of quotients of numbers.This device is used manually and it used the system of Arab Mathematics.It can be used to perform multiplication of numbers from 2-9

                                                                             

Cylindrical form of Napier bones     

(ii) Slide Rule

The idea of logarithm by Napier bones soon gave birth to an other Mechanical calculating device called slide rule or also known as colloquially in US .This device is used for basic multiplications and divisions and other calculations such as logarithm root and also trigonometry .

Construction:

A slide  rule consist of  two scales ;the Rule and the Slide.It also consist of a Transparent  moving piece of  piece of some material ,it is called  cursor.The cursor is highly capable to slide over the smooth surfaces called slide rule.

Although, its name is similar to a simple scale that is used to draw simple straight lines,But never be confused with it it is not that simple one.

                                                                           

                                                         

                                                              A slide rule