World population reaches 1.55 billion.

Max Planck formulates the quantum theory in physics. He will receive the Nobel Prize for physics in 1918.

Sigmund Freud publishes Die Traumdeutung, later translated as The Interpretation of Dreams.

Jose Enrique Rodo publishes Ariel, a work that heightens anti-U.S. sentiment among South American intellectuals.

In Japan the Police Regulations of 1900 institute a near-total ban on collective bargaining and the right to strike.

The Paris Metro (Chemin de Fer Metropolitain) opens, with more than six miles of track completed.

At the Paris Exposition, the elevator is unveiled to the public. An elevator of similar design, first patented by American Charles A. Wheeler in 1892, is installed in Bloomingdale's department store in New York the same year.

1 Jan.

A British protectorate is established over northern Nigeria.

20 Jan.

John Ruskin, influential English art critic and social reformer of the Victorian era, dies.

31 Jan.

John Sholto Douglas, eighth Marquess...