Periodic table (detailed cells)
Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev invented the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.
Desk
The basic desk forms were developed mostly in the 17th and 18th centuries. The modern ergonomic desk is a refinement of the mechanically complex drawing table or drafting table from the end of the 18th century.