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Primary sourceDocument1687

Principia Mathematica, Fold-out Diagram

Isaac Newton · 1687

A fold-out engraved diagram from Newton's 1687 Principia illustrating his geometric treatment of motion and force.

This diagram, from Newton's own Principia, illustrates the mathematical methods he devised to explain motion.

Engraved diagram on a cream page within a book, showing a curved comet path from Sol at left, with dated positions such as Nov. 25, Dec. 12, Jan. 5 and Mar. 5, labeled orbit lines and a sphere intersection line.
Isaac Newton, Philosophiae Naturalis Principia Mathematica, fold-out diagram, 1687. Wellcome Collection, London.

About this source

What it is

This fold-out page from Newton's Principia Mathematica (1687) contains an engraved diagram showing a curved path, likely tracing a comet's motion from the Sun, with dated positions and orbit lines. It is held by the Wellcome Collection in London.

Why it matters

Newton used geometric diagrams like this to demonstrate his laws of motion and gravitation mathematically. Such diagrams reveal how he combined observation, dates and geometry to prove his physical ideas rather than relying only on words.

Look closer

  • Why would Newton use a diagram instead of only writing in words?
  • What might the dated positions along the curve represent?
  • Why do you think this page folds out rather than sitting flat in the book?

This document is part of the curated material that grounds the AI version of Isaac Newton on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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