Dalton's wooden atomic models, c early 19th century.

These wooden balls, were the first models made to represent atoms and were used by John Dalton (1766-1844) to demonstrate atomic theory. He stated that matter is made up of small indivisible particles, or solid atoms. Dalton first published, in 1808, in a small book entitled A new system of Chemical Philosophy, Part 1, by John Dalton. The book had an enormous influence on the development of both chemistry and physics.