Blacks invented devices for handling sails, corn harvesters and an evaporating pan which revolutionized the method of refining sugar. Another inventor created a machine for the mass production of shoes that was used by the United Shoe Machinery Company.

J.H. Dickinson and his son were granted patents for devices connected with player pianos. Granville T. Woods patented more than 50 devices related to electricity that were assigned to General Electric and other major companies.

The U.S. Patent Office at the time maintained records for 1,500 inventions by blacks, an incomplete record, DuBois said. Black scientists did important work on insects and insanity.

Benjamin Banneker was a leading American scientist whose mathematical genius won the praise of Thomas Jefferson and led the slave owner to question notions of racial superiority.

Banneker played an important role in a survey as the nation's capitol was laid out and studied methods to promote peace, suggesting a secretary of peace in the president's cabinet, according to the book.

The book portrays Crispus Attucks, a runaway slave, as leading the fight against British soldiers that sparked the famous Boston massacre of 1770. Thousands of black soldiers fought on the American side of the Revolutionary War and distinguished themselves at the Battle of Bunker Hill and other sites.

Black soldiers and slaves helped saved New Orleans during the War of 1812, winning praise from General Andrew Jackson. The New York Times praised the bravery of black soldiers in the Civil War.

"Without the active participation of the Negro in the Civil War, the union could not have been saved, nor slavery destroyed, in the nineteenth century," DuBois wrote.

In fighting slavery, blacks forced the country to expand its democracy and wound up winning rights for poor whites who did not own property, DuBois argued. Their efforts also led to social reforms such as free public schools.

"Dramatically, the Negro is the central thread of American history," DuBois wrote. "The whole story turns on him whether we think of the dark and flying slave ship in the sixteenth century, the expanding plantations of the seventeenth, the swelling commerce of the eighteenth or the fight for freedom in the nineteenth."

Copyright 2009 The Associated Press.