The Henry Black papers contain personal and business correspondence addressed to Black, primarily concerning life on his family's farm in Carrollton, Illinois, and the marketing and sale of Black's patented hay harvesting machine. Personal correspondence dates almost exclusively to the Civil War era, though Black's correspondents only mentioned the war in passing; his sister Alice, parents, and cousins focused on farm life in Carrollton, and passed along news of family and friends while Henry worked in California. Black's cousin, Edward B. Hobson, wrote several letters about his studies at Shurtleff College in Alton, Illinois. Albert Gregory, another cousin, described his family's passage from San Francisco to Panama, where they saw several volcanoes and other exotic sights (March 8, 1863). Business correspondence comprises the bulk of the collection, and relates primarily to Black's hay harvesting pulley, which he marketed and sold throughout the Midwest and South. One early letter from James Hill in New Hampshire regards Hill's harness business, including wartime prices for his products and a printed circular offering his manufactured goods to military officials (December 2, 1864). The remainder of the material contains inquiries about Hay's machine, orders for the equipment, and positive feedback from customers. A series of later letters from the U. S. Wind Engine & Pump Company respond to Black's own inquiries about their windmills and other farm equipment.
Printed material includes 6 pamphlets about the process of obtaining a United States patent, a call for advertisers for the Boston Cultivator, and a request for sales agents for the Osage Orange Hedge Plants Company.