Governor-general of the Philippines Narciso Claveria, signs a decree to reform the country's calendar by skipping Tuesday, December 31, as a solution to anomalies that had existed since Ferdinand Magellan's arrival in 1521.

Narciso José Anastasio Clavería y Zaldúa, 1st Count of Manila was a Spanish army officer who served as the Governor-General of the Philippines from July 16, 1844, to December 26, 1849.

December 31 is the 365th day of the year in the Gregorian calendar. It is known by a collection of names including: Saint Sylvester's Day, New Year's Eve or Old Year's Day/Night, as the following day is New Year's Day. It is the last day of the year; the following day is January 1, the first day of the following year.

Ferdinand Magellan was a Portuguese explorer best known for having planned and led the 1519–22 Spanish expedition to the East Indies. During this expedition, he also discovered the Strait of Magellan, allowing his fleet to pass from the Atlantic into the Pacific Ocean and perform the first European navigation to Asia via the Pacific. Magellan was killed in battle in the Philippines and his crew, commanded by the Spanish Juan Sebastián Elcano, completed the return trip to Spain in 1522 achieving the first circumnavigation of Earth in history.

1521 (MDXXI) was a common year starting on Tuesday of the Julian calendar, the 1521st year of the Common Era (CE) and Anno Domini (AD) designations, the 521st year of the 2nd millennium, the 21st year of the 16th century, and the 2nd year of the 1520s decade.

August 16 is the 228th day of the year in the Gregorian calendar; 137 days remain until the end of the year.