# The History of the Slide Rule: Tracing the Invention and Development of This Tool

Jan 12, 2023

## Introduction

The slide rule is a tool used for calculations. It consists of two logarithmic scales that slide against each other, allowing for multiplication and division. The slide rule was invented in the 1600s and revolutionized mathematics. In this article, we explore the history of the slide rule, from its invention to its modern-day uses.

## History of the Slide Rule

The slide rule was first invented by English mathematician William Oughtred in 1622. He created the tool as a way to make calculations quicker and easier. Oughtred’s slide rule was made with two logarithmic scales, one fixed and one moveable, that could be used to multiply and divide numbers. Oughtred’s invention was met with great enthusiasm and quickly spread throughout Europe.

In 1630, French mathematician Pierre Vernier improved upon Oughtred’s design by adding a second moveable scale. This allowed for more precise measurements and calculations. Over the next few centuries, the slide rule continued to be developed and refined, becoming increasingly accurate and efficient.

## Timeline of the Slide Rule

So when was the slide rule first invented? The answer is 1622, when William Oughtred first conceived of the idea. From there, the slide rule continued to evolve over the years. In 1630, Pierre Vernier introduced his version of the tool with two moveable scales. In 1684, French philosopher Blaise Pascal refined the slide rule even further by adding a curved scale to the design.

In 1775, English inventor Edmund Gunter published his book On the Use and Construction of the Sector and Cross-Staff, which detailed his version of the slide rule. His design featured a curved scale and a moveable cursor for greater accuracy. Gunter’s design was further improved upon in 1859 by English mathematician Edward H. Moore. Moore’s version featured a moveable cursor and a linear scale marked with logarithms.

In 1881, American engineer Edwin Thacher patented what is now known as the modern slide rule. His design featured two moveable cursors, one fixed and one moveable, and two linear scales. Thacher’s design was the most advanced of its time and is still used today.

## Impact of the Slide Rule

The slide rule had a profound effect on mathematics and science. Before its invention, mathematicians were limited to using their own mental calculations or cumbersome tables of logarithms. With the slide rule, calculations became much faster and more accurate, allowing scientists to make more complex calculations than ever before.

The slide rule also had a major impact on engineering. Engineers were able to use the tool to make calculations for building bridges, roads, and other structures. The tool also allowed them to calculate forces, speeds, and other important factors. Without the slide rule, many of the engineering feats of the 20th century would not have been possible.

## Visual Guide to the Slide Rule

The slide rule has gone through many iterations over the years, each with its own unique design. To get a better understanding of the tool’s evolution, let’s take a look at some examples of how it has been used. The following images show various designs of the slide rule, from Oughtred’s original version to Thacher’s modern design.

This is William Oughtred’s original slide rule, which featured two logarithmic scales and a moveable cursor. It was the first iteration of the tool and was used to calculate multiplication and division.

This is Pierre Vernier’s improved version of the slide rule. His design featured two moveable scales, allowing for more precise measurements and calculations.

This is Edmund Gunter’s slide rule. His design featured a curved scale and a moveable cursor, making calculations even more accurate.

This is Edwin Thacher’s modern slide rule. His design featured two moveable cursors and two linear scales, making it the most advanced slide rule of its time.

## Conclusion

The slide rule is an important invention that revolutionized mathematics and science. It was first invented in 1622 by English mathematician William Oughtred and has since undergone many iterations and improvements. Today, the slide rule is still used by engineers and scientists around the world to make calculations and solve problems.

This article has explored the history and impact of the slide rule. We have traced its invention and development, from William Oughtred’s work in the 1600s to the modern day. We have provided a timeline of the tool’s evolution and shown how it has changed mathematics and our lives. Finally, we have showcased its design elements over time and provided examples of how it has been used.

#### By Happy Sharer

Hi, I'm Happy Sharer and I love sharing interesting and useful knowledge with others. I have a passion for learning and enjoy explaining complex concepts in a simple way.