Go back

Lewis H. Latimer’s Patent for the Process of Manufacturing Carbons (1882)

Publication
This document is an official patent drawing and specification for Lewis Howard Latimer’s invention titled "Process of Manufacturing Carbons." The patent was granted on January 17, 1882, as U.S. Patent No. 252,386.The signatures of witnesses and Latimer himself as the inventor are visible at the bottom of the document. In this patent, Latimer reimagined the process for making carbons for incandescent lamps. He proposed protecting the carbon strip in a cardboard envelope that would keep it from shrinking and breaking under the high heat of manufacturing. Latimer studied this problem carefully, he noted, “having qualified myself to take charge of producing the carbons for the lamps” in Hiram Maxim’s workshop. Latimer signed this patent over to Maxim’s U.S. Electric Lighting Company, but the extent of its use is not known. Latimer worked with Maxim on multiple improvements; by 1883, over 50,000 of the company’s lamps were being used in America.
Lewis H. Latimer’s Patent for the Process of Manufacturing Carbons (1882) picture number 1

Lewis H. Latimer was a pioneering Black inventor and engineer who played a role in the development and improvement of electric lighting technology. Latimer’s contributions to electrical engineering were often overlooked, but this patent stands as historical evidence of his role in shaping technological advancements in the late 19th century.

Latimer Family Papers (1870-1996 ) [QPL Full Collection]

(No Model.) L. H. LATIMER PROCESS OF MANUFACTURING CARBONS. No. 252,386. Patented Jan. 17, 1882. (Figure 1, Figure 2, and Figure 3 are technical diagrams illustrating the manufacturing process for carbon filaments.) Witnesses: Edw. Gulager, A. P. Ransom. Inventor: Lewis H. Latimer By Parker W. Page, Attorney. S. N. Ritch, Photo-Lithographer, Washington, D.C.