Licence: Attribution 4.0 International (CC BY 4.0)
Credit: Helmholtz pendulum, Berlin, Germany, 1895-1910. Science Museum, London. Source: Wellcome Collection.
Licence: Attribution 4.0 International (CC BY 4.0)
Credit: Helmholtz pendulum, Berlin, Germany, 1895-1910. Science Museum, London. Source: Wellcome Collection.