Tutorials Audio

Granville T. Woods: Talking to a Moving Train

By Infinite Creation · Profile

Historical photograph of Granville T. Woods.

At a Glance

Granville Tailer Woods (1856-1910) patented the synchronous multiplex railway telegraph in 1887, allowing messages to pass between moving trains and stations by induction from the rails. He held around sixty patents across railway, telegraph and electrical systems, and successfully defended his work against challenges including from Edison.

Lived: 1856-1910, United States
Anchor year: 1887, the multiplex induction telegraph
Strand: overlooked

Career

The problem as it stood

Trains could not communicate while moving. Dispatchers knew where a train had last been reported, not where it was, and collisions followed. Physical wires cannot connect to something in motion.

What he actually did

Woods used electromagnetic induction between a coil on the train and the telegraph line running beside the track, allowing messages to pass without contact and permitting several messages to share the line. He fought and won patent challenges over the work.

How it worked

A current in one conductor induces a current in a nearby one without connection. That is a form of wireless, near-field rather than radiative, but the same physics Hertz was demonstrating in the same decade, and it worked precisely because it needed no physical link to a moving object.

What it made possible

Practical train dispatch and a substantial safety improvement, and a demonstrated route to communicating with moving vehicles that predates radio telegraphy in service.

What happened to him

Woods worked as an independent inventor, frequently in litigation to defend patents, and sold rights to companies including General Electric and Westinghouse. He died in poverty in 1910 and was buried in an unmarked grave. A headstone was placed in 1975.

Where the credit landed

Woods was a prolific Black inventor operating without institutional backing in an era of legal segregation, defending patents against far better-resourced opponents and largely succeeding. His absence from general histories of communication owes nothing to the quality of the work. He is sometimes called "the Black Edison", a description that flatters Edison more than it serves Woods.

Known For

Induction is near-field wireless: same era as Hertz, different mechanism.
He won patent challenges against much better-resourced opponents, including Edison.
He died in poverty. His grave was unmarked until 1975.

Knowledge Base

What You'll Learn

Communicating with something that moves is a distinct problem, and it was solved before radio.

Near-field induction versus radiated waves

Induction couples energy between conductors close together relative to the wavelength: strong, short-range and requiring no tuning. Radiated waves travel indefinitely and need antennas, tuning and far more sophisticated receivers. Woods used the first because it was reliable with 1880s components. The same distinction still matters: contactless payment and wireless charging are induction. Broadcasting and mobile telephony are radiation.

Where This Fits

Woods's train telegraph was a transmission problem, the link at the centre of A History of Broadcast Technology.

FAQ

Q: What did Granville Woods invent?
A: Around sixty patented devices, most notably the synchronous multiplex railway telegraph of 1887, which let moving trains and fixed stations exchange messages by induction from the line beside the track.

Q: Was his work related to radio?
A: It used near-field electromagnetic induction rather than radiated waves, so it is a different mechanism, but it solved the same underlying problem of communicating with something in motion, and did so before radio telegraphy was in service.

Vocabulary

Multiplex. Carrying several separate messages over one channel at the same time. Multiplies the capacity of an existing line without laying more of it, which is why the idea recurs throughout communications.

Induction. Transferring energy between two circuits through a magnetic field rather than a direct connection. Allows a moving vehicle to communicate with fixed infrastructure without a physical link.

Telegraphy. Sending messages as coded electrical pulses rather than as speech. The first electrical communications medium, and the foundation on which telephony and radio were both built as extensions of the same idea.

Duplex. Communication in both directions. Half duplex alternates between sending and receiving, and full duplex does both at once, which requires separating the two signals somehow.

Sources

The induction telegraph patent was checked against the record. Checked 20 August 2026.

US Patent 373,915, Induction-Telegraph System. Woods's patent, granted 29 November 1887. It describes communication between moving railway trains and fixed points using helical conductors and induction, with no direct electrical connection between them.