This Month in Physics History

November 29, 1887: Granville Woods Patents the Induction Telegraph

The invention, which allowed stations to communicate with trains and prevent collisions, soon locked Woods in a patent battle — one of many in the prolific inventor’s life.

By Tess Joosse | October 13, 2023

Credit: Portrait from The Cosmopolitan Magazine in 1895; patents from US Patent Office, patents 373,915 and 373,383.

A portrait of Granville T. Woods.

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In February 1885, Granville T. Woods came across a troubling article in Scientific American. According to the story, an inventor named Lucius J. Phelps created a system for sending a telegraph message to a moving train. While this was good news for railway safety (“the risks of disaster on railways will, by this means, be greatly reduced from this time onward,” the story proclaimed), it was bad news for Woods. Four years earlier, he had designed a nearly identical invention, an “induction telegraph,” but had contracted a nasty bout of smallpox before he could patent or publicize it.

Soon Woods — then nicknamed the “Black Edison” for his inventive contributions — was locked in a patent investigation battle over the induction telegraph. It was just one in a long line of struggles Woods experienced trying to profit from his inventions. “He spent the majority of his adult life marginalized as an inventor, desperately struggling to secure funding and gain a respectable reputation for his work,” writes Rayvon Fouché in Black Inventors in the Age of Segregation: Granville T. Woods, Lewis H. Latimer, and Shelby J. Davidson.

Woods was born on April 23, 1856. Where, exactly, is a bit of a mystery. Many biographies say Ohio, but Woods himself claimed he was born in Australia, probably a lie he told “to garner respect and dissociate himself from slavery in the United States,” according to his obituary published in 2019 in The New York Times.

Other facts about Woods’ early life are similarly cloudy. He possibly received some technical schooling and worked for an iron company, as a firefighter, and aboard a British steamer ship. In the 1870s, he found employment as an engineer on the Dayton and Southeastern Railroad in Ohio, where it’s likely some of his later train- and electricity-focused inventions took root.

In later patent-interference case testimony, Woods described how a telegraph operator in a town along the rail route showed him how to use the machine. Invented in the 1830s and, by 1880, the gold standard for long-distance communication, the electrical telegraph worked by pressing a button to form electrical circuits and pass signals over wires, to be received by a telegraph sounder in a pattern of Morse code dashes and dots that could be translated into a message.

On another visit to the town in late 1880, Woods rode an elevator in the local hotel and invented a method for improving the elevator’s signaling between floors with induction. The idea was to attach one wire, wound around a metal core, from the bottom floor to the elevator. This wire would pass through another wire that was wound around a spool and connected to each floor of the building. A passenger on one floor could push a button and complete a circuit with the first wire, while an impulse inductively moved to the second wire, alerting the elevator operator to send the car on up.

Woods ended up abandoning the idea, and he quit his job on the Ohio railroad. But he kept inventing, and soon settled in Cincinnati without a steady job. “Woods’s day-to-day activities can best be described as surviving and even hustling,” writes Fouché. Woods saw inventing as his best way to make money.

Woods’ early experiences working on the railroad likely taught him the danger posed by two trains on a collision course. Stations couldn’t reliably communicate with moving trains, and early visual signaling systems were imperfect and prone to error. “The public prints give us almost daily accounts of railway collisions in one section of the country or another,” read the 1885 article in Scientific American.

In early 1881, Woods designed a railway communication system using existing telegraph lines, which ran along or near many train routes. One wire, connected to a train station’s telegraph transmitter-receiver, would be routed above the tracks on poles or connected to a wire embedded along the tracks with an inductor. Another wire and inductor would be carried by the train car itself, accompanied by a transmitter and other apparatuses for receiving a telegraph message. As the train chugs along, its inductor passes over the inductor embedded in the tracks, creating mutual inductance through which electrical signals can be passed.

Before Woods could test the creation or file a patent, he fell ill with smallpox in August of 1881. For months, Woods languished in bed, and even after he recovered, his health was never the same.

After his recuperation, he built several models of the induction telegraph and refined its design. By the time he read of Phelps’ work in Scientific American, Woods had also worked on many other ideas, including a steam boiler furnace, an electromagnetic brake, and several telephonic devices.

But the article kicked his induction telegraph efforts into high gear. He applied for a patent on May 21, 1885, secured funding from a local dentist, built a ten-foot-long model train track to show it off with, and had it tested by telegraph operators.

Several months later, the patent office replied. Phelps had filed on Feb. 20, 1885 — a day before the article was published, and three months before Woods. But because neither man had been actually granted the patent yet and the US operated under a “first-to-invent” rather than “first-to-file” system at the time, the two parties went to court to establish priority.

Woods and his lawyer produced documents and witnesses testifying he created the invention in 1881, while Phelps could not prove he did earlier than October 1884. The judge ruled in Woods’ favor, and after an appeal from Phelps was struck down, he finally received the patent for the induction telegraph system on Nov. 29, 1887.

According to Fouché, at least 17 of the 45 patents filed by Woods over his lifetime would be involved in court proceedings, including his idea for a third rail to power electric subway trains from below. And when he died in 1910 from smallpox complications, he was buried in an unmarked grave. He struggled financially, professionally, and personally throughout his life, writes Fouche. “The experiences of Granville Woods have shown how … a great idea does not necessarily guarantee success.”

In recent decades, Woods’ legacy has been reinvigorated. He was honored with a commemorative New York City subway MetroCard in 2004 for his contribution to the third rail system. In 2006, he was inducted into the National Inventors Hall of Fame, only the second Black inventor to receive the distinction. And in 1975 — 65 years after the inventor’s death — Woods’ unmarked gravesite in Queens, New York, was finally given a headstone. An article in The New York Times quoted a historian, M.A. Harris, who attended the ceremony.

“There had been no research done on Woods since 1887,” Harris said. “Yet this man had performed such magic.”

Tess Joosse is a science journalist based in Michigan.