= Henry Cavendish
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<Henry Cavendish> used a <torsion balance> to infer the mean <density> of the <Earth>. Nearby lead masses exert a <gravitational force> on smaller masses carried by a suspended horizontal arm. The wire's restoring <torque> opposes the resulting <angular displacement>; the arm's <oscillation> period calibrates that response. Moving the attracting masses to opposite sides reverses the deflection. Comparing this measured <gravitational force> with terrestrial <gravity> then determines the mean <density> of the <Earth>. To reduce <convection> caused by uneven heating, he enclosed the apparatus and observed its scale through telescopes from outside the room.<Experiments to Determine the Density of the Earth by Henry Cavendish>[1798, pp. 469–475: apparatus, oscillation calibration, reversed positions and thermal-air-current precautions]{ref}
Experimental natural philosopher who measured terrestrial gravitational attraction and inferred the mean <density> of Earth in 1798.
\Image[https://commons.wikimedia.org/wiki/Special:Redirect/file/Henry_Cavendish,_Chemist._1731-1810_Wellcome_M0014171.jpg?width=260]
{title=Portrait of <Henry Cavendish>}
{description=Wellcome Library, London / Wellcome Collection; after a drawing by Alexander in the British Museum. https://creativecommons.org/licenses/by/4.0/[CC BY 4.0], via Wikimedia Commons.}
{source=https://commons.wikimedia.org/wiki/File:Henry_Cavendish,_Chemist._1731-1810_Wellcome_M0014171.jpg}
{width=260}
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