1842: English social reformer Edwin Chadwick publishes "Sanitary Conditions of the Labouring Population of Great Britain." The report, which exposes the poor conditions and high disease rate among England's factory workers, shocks the public and raises the need for reform.

Today: While the living conditions of workers in advanced nations remain acceptable, annual United Nations reports on conditions in Third World countries show workers experience ongoing poverty, disease, and occupational danger.

1843: A British force of 2,800 men under Sir Charles Napier defeats a 30,000-man Baluch Army, forcing India's Muslim emirs of Sind to surrender their independence to the East India Company.

Today: Great Britain relinquishes Hong Kong, the jewel of its remaining Asian colonial possessions, to the Republic of China. To many, the event symbolizes the increasing transfer of European power to other parts of the world.

1846: After a series of crop failures, Parliament repeals the...