Telluric screw of de Chancourtois, c 1862.
© Science Museum / Science & Society Picture Library
Model. In 1862 BEguyer de Chancourtois was the first person to make use of atomic weights to produce a clasification of periodicity. He drew the elements as a continuous spiral around a cylinder divided into 16 parts. The atomic weight of oxygen was taken as 16 and was used as the standard against which all the other elements were compared. Tellurium was situated at the centre of his system, prompting de Chancourtois to name it the 'Vis Tellurique', or telluric screw. In 1869 Mendeleev published his first periodic table, the system of clasifying the elements which is still used today.