The Lost Art of Logarithms

3 min read Original article ↗
Charles Petzold holding massive slide rule

A web-based book-in-progress by
Charles Petzold
wherein is explored the utility, history, and ubiquity of that marvelous invention,
logarithms
including what the hell they are; with some demonstrations of their primary historical application in plane and spherical trigonometry; plus, that extraordinary tool known as the
slide rule
is fully explored in theory and use.

  • This is a work in progress

Chapter titles in green are pretty much finished; no substantial changes are anticipated but small edits, corrections, or cosmetic fixups might be required.

Chapter titles in red are unfinished and currently in a state of flux.

Chapter titles in black are not yet begun.

Nothing has yet been professionally edited. I anticipate that this book will be completed by year-end 2027.

  • It is best viewed on a desktop or laptop computer

I've been developing the pages in Edge using Visual Studio Code running under Windows 11 on a Microsoft Surface Pro 9. I've also been testing the pages in Chrome on that machine, and in Safari on a Mac Mini running Sequoia, and in Chrome (version 126, it says) on an Asus Chromebook.

However, my iPad Mini running iOS 12.5.7 has several problems with these webpages, and the pages often become quite awkward on phones.

Chapter 1. The 400-Year-Old Computer

Part I. The Book of Vlacq

Chapter 2. The Conquest of Multiplication

Chapter 3. The Magic Demystified

Chapter 4. Powers and Roots as Well

Chapter 5. The Logarithmic Scale

Chapter 6. Calculating a Logarithm by Hand

Part II. Logarithms Everywhere

Chapter 7. Binary Logarithms

Chapter 8. The Natural e

Chapter 9. Time and Space

Chapter 10. Sound and Music

Chapter 11. Logarithmic Measures

Chapter 12. Log-Log and Semi-Log Graphs

Part III. Back to Vlacq: The Trigonometric Connection

Chapter 13. The Pythagorean Breakthrough

Chapter 14. Beyond the Straight Right Triangle

Chapter 15. The Ubiquitous Sinusoid

Chapter 16. Mapping Out the Earth

Chapter 17. Reaching for the Stars

Part IV. Mathematicians at Work

Chapter 18. John Napier’s Life and Reformationary Times

Chapter 19. Countdown to the Apocalypse

Chapter 20. Conceiving the Logarithm

Chapter 21. The Handoff to Henry Briggs

Part V. Logarithms at Your Fingertips

Chapter 22. Edmund Gunter’s Mathematical Tools

Chapter 23. William Oughtred’s Brilliant Idea

Chapter 24. Peter Mark Roget and the Log-Log Scale

Chapter 25. Amédée Mannheim and the Modern Slide Rule

Chapter 26. Slide Rules Go Cylindrical

Chapter 27. The Obstinacy of Charles Babbage

Back Matter

About the Author