Zertsalo displaying decrees of Peter the Great in Russian Empire offices

This curious object at the centre of the table was to be found in every government office of the Russian Empire. It is the zertsalo ("mirror"), a special prism of wood or metal, surmounted by the double-headed imperial eagle, on which were displayed the decrees of Peter I addressed to officials and assessors. The zertsalo stood in many official premises right up to the twentieth century as a reminder to observe the interests of the state and to do one's duty