Production of an Original Surface Plate (Engineering Reminiscences, Chapter XXI)

TL;DR — A 1908 account of making a truly flat plane by hand: scrape three plates against each other until all three agree.

Chapter XXI of Charles T. Porter’s Engineering Reminiscences (John Wiley & Sons, 1908), which describes Joseph Whitworth’s method of producing an original standard surface plate by scraping. Because any two plates can match while both are curved, flatness comes from rotating comparisons among three, so precision can be made from nothing but care.

What it is: a six-page excerpt from a public-domain book, and a classic text on how precision manufacturing bootstraps itself.

Where this came from

• r/obscurePDFs post, April 2020 — “Hand Scraping a Truly Flat Plane”. Routing record: The obscurePDFs Subreddit
• Archived copy (Google Drive): Google Drive

6 pages. A copy is archived locally against link rot; the header links the original source.