This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Ruprechtsche Waage. Weighing prototype kilogram with precision Ruprecht balance around The balance is manipulated from distance by the man on the right using long extension controls to avoid his body temperature upsetting the delicate thermal equilibrium of the balance causing convection currents which would bias the measurement