1720 in science

The year 1720 in science and technology involved some significant events.

Astronomy

 * February 10 – Edmond Halley is appointed as Astronomer Royal of England.

Medicine

 * May – First patient admitted to the Westminster Public Infirmary, predecessor of St George's Hospital, London.
 * Dr Steevens' Hospital is established at Kilmainham, Dublin.
 * Great Plague of Marseille, the last major outbreak of bubonic plague in Europe.
 * English physician Richard Mead publishes A Short Discourse concerning Pestilential Contagion, and the Method to be used to prevent it.

Physics

 * Willem 's Gravesande publishes Physices elementa mathematica, experimentis confirmata, sive introductio ad philosophiam Newtonianam, an introduction to Newtonian physics, in Leiden.

Technology

 * A theodolite is developed by Jonathan Sisson of England.
 * Pinchbeck is invented by English watchmaker Christopher Pinchbeck; it is an alloy of 83% copper and 17% zinc, creating a strong, hard-wearing metal which has the appearance and weight of 20 carat gold.
 * An early chronograph is invented which has only mechanical parts in it.
 * Henry de Saumarez (of the Channel Islands) produces an instrument called the Marine Surveyor intended to measure a ship's velocity.
 * A single-action five-pedal harp is developed by Jacob Hochbrucker of Bavaria which can raise the pitch of the selected strings by a half step.
 * approx. date – Joseph Williamson uses a differential gear in a clock.

Births

 * January 30 – Charles De Geer, Swedish industrialist and entomologist (died 1778)
 * March 13 – Charles Bonnet, Genevan naturalist and philosophical writer (died 1793)
 * July 18 – Gilbert White, English naturalist (died 1793)
 * October 8 – Geneviève Thiroux d'Arconville, French novelist, translator and chemist (d. 1805)
 * November 5 - Jean Baptiste Christophore Fusée Aublet, French pharmacist and botanist (died 1778)
 * December ? – James Hargreaves, English inventor (died 1778)
 * approx. date – Dmitry Ivanovich Vinogradov, Russian chemist and (died 1758)

Deaths

 * December 29 – Maria Margarethe Kirch, German astronomer (born 1670)
 * David Gregory, Scottish physician and inventor (born 1625)