science · 30 September 1927 · 97 years ago
In 1927, the 7th Conférence Générale des Poids et Mesures (CGPM) slightly modified the definition of the metre. It was still defined as the distance between two lines on the International prototype metre, but it was now specified that it should be supported horizontally on two cylinders of less than 1 cm diameter, placed symetrically, and 571 mm apart.
OnThisDay.net