 The next step in the development of structural theory came when James Dewar (1842–1943) and August Hofmann (1818–1892) developed physical models corresponding closely to Crum Brown’s formulae (Meinel 2004). Dewar’s molecules were built from carbon atoms represented by black discs placed at the centre of pairs of copper bands. In Hofmann’s models, atoms were colored billiard balls (black for carbon, white for hydrogen, red for oxygen etc.) linked by bonds. Even though they were realized by concrete three-dimensional structures of croquet balls and connecting arms, the three-dimensionality of these models was artificial. The medium itself forced the representations of atoms to be spread out in space. But did this correspond to chemical reality?