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Astronomy

• September 10 – Edward Pigott identifies the variable star Eta Aquilae from York, England.
• October 19 – John Goodricke begins his observations of the variable star Delta Cephei from York.

Biology

• Publication of the Annals of Agriculture edited by Arthur Young begins in Great Britain.
• Peter Simon Pallas begins publication of Flora Rossica, the first Flora of Russia.

Chemistry

• L'Abbé René Just Haüy states the geometrical law of crystallization.¹
• Antoine Lavoisier pioneers stoichiometry.
• Citric acid is first isolated by Carl Wilhelm Scheele, who crystallizes it from lemon juice.²³
• Cholesterol is isolated.

History of science

• Publication of David Bourgeois' Recherches sur l'art de voler, depuis la plus haute antiquité jusque'a ce jour in Paris, the earliest work on the history of flight.

Mathematics

• Carl Friedrich Gauss, at the age of seven, pioneers the field of summation with the formula summing 1:n as (n(n+1))/2.

Medicine

• 11 February – Royal College of Surgeons in Ireland chartered.
• 12 March — Appointment of the French Royal Commission on Animal Magnetism (the Commission's Report was presented to King Louis XVI on 11 August 1784).
• Madame du Coudray, pioneer of modern midwifery in France, retires.
• Benjamin Franklin makes the first known specific reference (in a letter) to the wearing of bifocal spectacles.⁴
• John Hunter first describes the condition phlebitis.

Paleontology

• The first description of a Pterodactylus fossil is made by Cosimo Alessandro Collini, although he is unable to determine what kind of creature it is.⁵⁶⁷

Physics

• January 15 – Henry Cavendish's paper to the Royal Society of London, Experiments on Air, reveals the composition of water.⁸
• Jean-Paul Marat publishes Notions élémentaires d'optique (Elementary Notions of Optics)

Surveying

• William Roy measures the baseline for the Anglo-French Survey (1784–1790) linking the observatories of Paris and Greenwich. The measurement is accurate to within a few inches in a distance of over 280,000 ft., an unprecedented accuracy for this time. Roy is awarded the Copley Medal in the following year.⁹

Technology

• April 28 – James Watt receives a British patent for his parallel motion and other improvements to the steam engine.¹⁰
• June 4 – Élisabeth Thible becomes the first woman passenger in a hot-air balloon, at Lyon, France.¹¹
• August 21 – Joseph Bramah receives his first lock patent in London.
• Rev. Dr. Edmund Cartwright designs his first power loom in England.
• Henry Cort of Funtley, England, applies the coal-fired reverbatory furnace to the puddling process for conversion of cast to wrought iron.¹²

Awards

• Copley Medal: Edward Waring¹³

Births

• March 12 – William Buckland, English geologist and paleontologist (died 1856)
• June 3 – William Yarrell, English zoologist and bookseller (died 1856)
• June 17 – Andrew Crosse, English 'gentleman scientist', pioneer experimenter in electricity (died 1855)
• July 22 – Friedrich Bessel, German mathematician (died 1846)
• September 1 – Thomas Frederick Colby, English cartographer (died 1852)

Deaths

• May 12 – Abraham Trembley, Genevan naturalist (born 1710)
• September 1 – Jean-François Séguier, French astronomer and botanist (born 1703)
• September 4 – César-François Cassini de Thury, French astronomer (born 1714)

References

1. Haüy, René Just (1784). Essai d'une théorie sur la structure des crystaux. Paris: Gogué. ↩

2. Scheele, Carl Wilhelm (1784). "Anmärkning om Citron-saft, samt sätt at crystallisera densamma" [Note about lemon juice, as well as ways to crystallize it]. Kungliga Vetenskaps Academiens Nya Handlingar [New Proceedings of the Royal Academy of Science]. 2nd series (in Swedish). 5: 105–109. https://babel.hathitrust.org/cgi/pt?id=mdp.39015009215438;view=1up;seq=115 ↩

3. Graham, Thomas (1842). Elements of chemistry, including the applications of the science in the arts. London: Hippolyte Baillière. p. 944. Retrieved 2010-06-04. https://archive.org/details/elementschemist00grahgoog ↩

4. The College of Optometrists. "The 'Inventor' of Bifocals?". Archived from the original on 13 June 2011. Retrieved 2011-06-21. https://web.archive.org/web/20110613044912/http://www.college-optometrists.org/en/knowledge-centre/museyeum/online_exhibitions/artgallery/bifocals.cfm ↩

5. Collini, C. A. (1784). "Sur quelques Zoolithes du Cabinet d'Histoire naturelle de S.A.S.E. Palatine & de Bavière, à Mannheim". Acta Theodoro-Palatinae Mannheim 5 Pars Physica: 58–103. ↩

6. Taquet, P.; Padian, K. (2004). "The earliest known restoration of a pterosaur and the philosophical origins of Cuvier's Ossemens Fossiles". Comptes Rendus Palevol. 3 (2): 157–175. doi:10.1016/j.crpv.2004.02.002. /wiki/Doi_(identifier) ↩

7. Unwin, David M. (2006). The Pterosaurs: From Deep Time. New York: Pi Press. ISBN 0-13-146308-X. 0-13-146308-X ↩

8. Cavendish, Henry (1784). "Experiments on Air" (PDF). Philosophical Transactions of the Royal Society of London. 75: 372–384. doi:10.1098/rstl.1785.0023. JSTOR 106582. https://zenodo.org/record/1432276/files/article.pdf ↩

9. Roy, William (1785). "An Account of the Measurement of a Base on Hounslow-Heath". Philosophical Transactions of the Royal Society of London. 75: 385–480. doi:10.1098/rstl.1785.0024. https://archive.org/details/philtrans01222507 ↩

10. No. 1432. ↩

11. Gazette d'Amsterdam 25 June 1784; Journal des sçavans November 1784 pp. 760-762. /wiki/Gazette_d%27Amsterdam ↩

12. Gales, W. K. V. (1981). Ironworking. Princes Risborough: Shire. p. 8. ISBN 0-85263-546-X. 0-85263-546-X ↩

13. "Copley Medal | British scientific award". Encyclopedia Britannica. Retrieved 21 July 2020. https://www.britannica.com/science/Copley-Medal ↩