A little wonder, every day

Fact 1265 — Dalton and color vision

Титульна AI-згенерована ілюстрація / AI-generated cover illustration. Фотореалістична реконструкція робочого столу натураліста з рукописним зошитом і ботанічними зразками; не є автентичним предметом Дальтона та не моделює його сприйняття.

Thomas Phillips, *John Dalton*, 1835; portrait held by the National Portrait Gallery, London. Public-domain painting/reproduction (Phillips died 1845; Commons applies PD-Art/PDM). [Commons file page](https://commons.wikimedia.org/wiki/File:John_Dalton_by_Thomas_Phillips,_1835.jpg). Saved 623×800 JPEG and visually checked 2026-10-16. Portrait identifies Dalton but does not itself document his color-vision research.

AI-generated symbolic illustration of a botanical flower and contrasting color impressions. It is not a historical artifact or a scientifically accurate simulation of Dalton’s perception. Creator: OpenAI image generation. No external media or reuse license applies.

Digitized page 36 from John Dalton’s 1794 *Extraordinary Facts Relating to the Vision of Colours*, a primary source documenting his observations. [Original asset page](https://commons.wikimedia.org/wiki/File:Extraordinary_Facts_Relating_to_the_Vision_of_Colours-_With_Observations_-_DPLA_-_9888a1fc5bcf7520ccdf81a15a0ed40f_(page_10).jpg). Creator: John Dalton; digitized by the Science History Institute and contributed via DPLA/PA Digital. Public domain in the United States. Resized to 1047×1600 JPEG; visually checked 2026-10-20.

Eight Ishihara color-vision test plates, a later diagnostic context image (not a test of Dalton and not a simulation of his vision). [Original asset page](https://commons.wikimedia.org/wiki/File:Eight_Ishihara_charts_for_testing_colour_blindness,_Europe_Wellcome_L0059164.jpg). Credit: Science Museum, London / Wellcome Images; author metadata: Wellcome Library, London. CC BY 4.0 ([license](https://creativecommons.org/licenses/by/4.0)); attribution: “Science Museum, London / Wellcome Images,” with link to license and indication of edits. Resized to 1600×1199 JPEG; visually checked 2026-10-20.

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Титульна AI-згенерована ілюстрація / AI-generated cover illustration. Фотореалістична реконструкція робочого столу натураліста з рукописним зошитом і ботанічними зразками; не є автентичним предметом Дальтона та не моделює його сприйняття.

Listen to fact0:00 / —

John Dalton himself had a color-vision deficiency and in 1794 gave the first recorded account of it to the Manchester Literary and Philosophical Society; he published an expanded paper in 1798. Dalton incorrectly thought the cause was an unusual blue tint in the eye’s vitreous humor. In 1995, DNA analysis of his preserved eye showed that he had deuteranopia, a form of red-green color-vision deficiency.