Imagine a world just 60 years ago without PCs or even calculators, but a time when there was an increasing demand for very detailed calculations.
Slide rules such as this 20 inch example were the principal instruments for mathematical calculation until the development of the electronic calculator in the 1970s. It played an incalculable role in the design and development of all manner of manufactured goods, and thus helped to create the modern world in a most fundamental way. This example belonged to my late father, Victor Knight, who used it inter alia in the design of the Thunderbird surface-to-air missile and the Blue Water nuclear missile of the 1950s.
When Britain was an emerging imperial power and subsequently the first industrial nation, an Englishman, William Oughtred (1574-1660 is credited with developing the slide rule in the 1600s. It was based on the development of logarithms by the Scotsman John Napier (1550-1617).