Black History Month Spotlight: Celebrating ‘Black Edison’ Granville Woods

February 26, 2024 by Duane Benson

To celebrate Black History Month, we spotlight American engineer Granville T. Woods, who held more than 50 patents and invented the Synchronous Multiplex Railway Telegraph.

Granville T. Woods (April 23, 1856–January 30, 1910) is remembered today for his pioneering work on the telegraph and electric railways. In the late 1800s, rail transportation and the telephone/telegraph were two of the hottest high-tech industries of the day. Woods delivered major breakthroughs in both and supported himself as an inventor and manufacturer, earning himself the nickname "Black Edison".


Granville T. Woods

Granville T. Woods and two of his patents. Image courtesy of American Physical Society

Despite the societal challenges Woods faced due to his race, he is widely recognized as the first African American mechanical and electrical engineer of the post-Civil War era and filed dozens of patents that critically shaped communication technology.


Working Around Prejudice Along the Way

In the 1860s and '70s, formal education often took a backseat to work; for impoverished Black children, even in the Northern cities where Woods grew up, it was virtually nonexistent. Although Granville left grade school at age 10 to work to help support his family, he maintained a thirst for learning.

He continued an informal education by reading books about electricity that others had checked out from the local library for him; the library did not issue books to Black people at the time. As he got older, Woods worked in steel mills and railroad machine shops to learn on the job. It was during his time working for railroads that he started forming the ideas that would become his great innovations.


Trains, Telegraphs, and Telephones

Over a century ago, some towns and cities were just starting to be connected by wire and rail. Trains ran between cities and telegraph and telephone lines often ran in parallel to the train tracks. Although the train and the telegraph were physically close, they were electrically isolated. Trains could not communicate up and down the line without stopping at a station, and there was no way to tell where a train was on the line until you could see the belching smoke as the engine approached the station. 

In 1887, Woods invented the multiplex telegraph, also called the induction telegraph.  The multiplex telegraph used a battery-powered electromagnet placed under the train car and connected to the car’s telegraph system. It inductively coupled with coils in the tracks, allowing for synchronous bi-directional telegraph or telephone conversations while in motion. It also allowed the train dispatch office to locate the trains on the line. 

Woods devised a related system that allowed both telephone and telegraph signals to share the same line. Before the innovation, telephone (voice calls) and telegraph (the 1800’s version of data traffic) required separate wires—a very expensive prospect for the time. By combining the signals, the costs of wiring up cities dropped considerably. Alexander Graham Bell purchased this patent, giving Woods funding for furthering his career as an inventor.


Bringing Power to the Train

The first trains powered by external combustion steam engines were noisy, fuel- and water-hungry, smokey, and occasionally explosive. Operators saw the emerging electric motors as a safer and more economical alternative to steam. However, electric trains were of limited use because it was difficult to get enough power to the motors.


Patent illustration for Woods’ electric train third-rail pick-up

Patent illustration for Woods’ electric train third-rail pick-up. Image used courtesy of USPTO

In 1901, Woods invented a pick-up device that delivered large currents through a hot “third rail.” Most heavy electric and light rail systems still use this system to this day. The viable third rail allowed train companies to use electric rail systems for local routes where clean and quiet electric propulsion made more sense and leave combustion engines (external and then internal) to long haul routes where the steam disadvantages were less of an issue. 


A Worthy Legacy Should Not Be Forgotten

Woods created significant inventions in the fields of telegraphy, telephony, and electric railroads. He had nearly 60 patents issued for his innovations. He even prevailed in a patent suit brought by Thomas Edison. After the lawsuit, Edison offered Woods a partnership, but Woods declined and formed the Woods Electric Company to continue his work. In addition to the power pickup and the inductive telegraph, Woods’ inventions improved electric subway braking systems, subway tunnels, theater dimmers, and electric cars. 

Woods passed away in 1910 from complications related to a case of smallpox when he was younger. His grave in Queens, New York, lay unmarked until 1975 when historian M.A. Harris solicited donations from the companies to which he had sold inventions and purchased a headstone. These companies included Westinghouse, General Electric, and American Engineering. 

In 2004, New York City’s Transit Authority memorialized Woods and his contributions with exhibits in train and bus stations and a commemorative metro card. In 2006, Woods was posthumously inducted into the National Inventors Hall of Fame.