The dot was introduced as a symbol for multiplication by Leibniz. On July 29, 1698, he wrote in a letter to Johann Bernoulli: "I do not like X as a symbol for multiplication, as it is easily confounded with x.
Gottfried LeibnizI also take it as granted that every created thing, and consequently the created monad also, is subject to change, and indeed that this change is continual in each one.
Gottfried Leibniz