Around 1900, the Patent Office conducted a survey to gather information about Black inventors and their inventions. Letters were sent to patent attorneys, company presidents, newspaper editors, and prominent African-Americans.
Henry Baker recorded the replies and followed-up on leads. Henry Bakers research also provided the information used to select Black inventions exhibited at the Cotton Centennial in New Orleans, the Worlds Fair in Chicago, and the Southern Exposition in Atlanta.
By the time of his death, Henry Baker had compiled four massive volumes.