Periodic table
Russian chemistry professor Dmitri Mendeleev and German chemist Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively. Mendeleev's table was his first published version; that of Meyer was an expanded version of his (Meyer's) table of 1864. They both constructed their tables by listing the elements in rows or columns in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat.
Dispilio Tablet
The Dispilio tablet is a wooden tablet bearing inscribed markings, unearthed during George Hourmouziadis's excavations of Dispilio in Greece, and carbon 14-dated to 5202 (± 123) BC. It was discovered in 1993 in a Neolithic lakeshore settlement that occupied an artificial island near the modern village of Dispilio on Lake Kastoria in Kastoria, Western Macedonia, Greece.