International Prototype Kilogram. 19th-century illustration of the International Prototype Kilogram (IPK), the original standard kilogram commissioned in 1875 by the General Conference on Weights and Measures (CGPM) and held by the International Bureau of Weights and Measures (BIPM) in Sevres, France. Under an international treaty, copies of this standard weight were distributed worldwide. The IPK and its copies are 39 millimetres in diameter, 39 millimetres high, and made of a platinum-iridium alloy (90 percent platinum; 10 percent iridium). This illustration is from 'Physique Populaire' (Emile Desbeaux, 1891). | |
Licence : | Droits gérés |
Crédit: | Science Photo Library |
Taille de l’image : | 5980 px × 2923 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |