1723 in science

Geophysics

• George Graham discovers diurnal variation in Earth's magnetic field.
• Antoine de Jussieu publishes De l'Origine et des usages de la Pierre de Foudre on the origins of fossils, prehistoric stone tools and meteorites.

  Optics

• Giacomo F. Maraldi makes the first observation of the Arago spot, unrecognized at this time.

  Births

• January 5 - Nicole-Reine Lepaute, French astronomer
• January 31 - Petronella Johanna de Timmerman, Dutch scientist
• February 17 – Tobias Mayer, German cartographer, astronomer and physicist
• April 30 – Mathurin Jacques Brisson, French zoologist
• Saverio Manetti, Italian natural historian

  Deaths

• August 26 – Anton van Leeuwenhoek, Dutch pioneer of the microscope