Home›Open Questions›When was the photometer invented, and by whom?Open QuestionsWhen was the photometer invented, and by whom?Citation FormatsGeneral ReferenceGeneral Reference Citation TextScience Atlas. "When was the photometer invented, and by whom?." Accessed August 30, 2026. https://science.interactiveatlas.org/open-questions-index/when-was-the-photometer-invented.Copy General ReferenceAPA StyleAPA Style Citation TextScience Atlas. (n.d.). When was the photometer invented, and by whom?. Retrieved August 30, 2026, from https://science.interactiveatlas.org/open-questions-index/when-was-the-photometer-inventedCopy APA StyleBibTeXBibTeX Citation Text@misc{scienceatlas-when-was-the-photometer-invented-and-by, author = {Science Atlas}, title = {When was the photometer invented, and by whom?}, year = {2026}, url = {https://science.interactiveatlas.org/open-questions-index/when-was-the-photometer-invented}, note = {Accessed August 30, 2026} }Copy BibTeXOpen QuestionCross-Tradition ConnectionsSourcesComments (0)Reader Challenges (0 open reader challenges)Open QuestionWikipedia's Photometer article states three photometer types (Rumford's, Ritchie's, and shadow-extinction types) were already in common use by 1861, but names no invention year or event for the instrument itself. The existing invented edge already credits Benjamin Thompson (Count Rumford), but neither his own Wikipedia biography nor the Photometer or Photometry (optics) articles state a year. A web search found a plausible date, Rumford's 1794 paper in Philosophical Transactions vol. 84, but the corroborating page (Citizendium) returned HTTP 403 and was not visited, so it is not citable under the quote-capture duty.What would resolve this A fetchable, quotable page (not blocked) that states the year Rumford, Ritchie or an earlier figure such as Bouguer or Lambert first built or described a working photometer, ideally naming the specific publication (Rumford's 1794 Philosophical Transactions paper is the leading candidate).OpenHistory of sciencePhotometer (Wikipedia)Cross-Tradition ConnectionsQuestion OnPhotometer, Instruments Well-attested Source Photometer (Wikipedia)tier 2SourcesPhotometer (Wikipedia)tier 2WikipediaHistory sectionView the SourceComments (0)No comments yet. Be the first to share a thought.Sign in to join the discussion.Reader Challenges (0 open reader challenges)No disputes yet. Spotted an error or a better source? Open the first one.Sign in to dispute this or suggest a correction.View At A Past YearThe atlas records no dated fact of its own for this entry, so there is no other year to choose.Show This Year