Periodic table
The organization of the periodic table can be used to derive relationships between the various element properties, and also to predict chemical properties and behaviours of undiscovered or newly synthesized elements. Russian chemist Dmitri Mendeleev published the first recognizable periodic table in 1869, developed mainly to illustrate periodic trends of the then-known elements. He also predicted some properties of unidentified elements that were expected to fill gaps within the table. Most of his forecasts proved to be correct. Mendeleev's idea has been slowly expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour. The modern periodic table now provides a useful framework for analyzing chemical reactions, and continues to be widely used in chemistry, nuclear physics and other sciences.
Beda Venerabilis' Easter cycle
In the year 616 an anonymous scholar extended Dionysius Exiguus' Easter table to an Easter table covering the years 532 up to and including 721. Dionysius' table was published in 525 and only a century later accepted by the church of Rome, which from the third century up till then had given preference to go on using her own, relatively inadequate, Easter tables. From about the middle of the seventh century all controversy between Alexandria and Rome as to the correct date of Easter ceased, as both churches were now using identical tables.