# Tesla is granted U.S. Patent 381,968 for an electro-magnetic motor

Date: 1888

## The fact

On 1 May 1888 the United States issued Patent 381,968 to [Nikola Tesla](/people/nikola-tesla) for an electro-magnetic motor using a rotating magnetic field. Related patents issued the same day covered electrical transmission of power. The U.S. patent is this Fact; uniqueness against Ferraris is not.

Patent 381,968 for an electro-magnetic motor (1888-05-01).

## Context

Commutator motors sparked and wore. A self-starting AC motor without brushes is the system-relevant claim. Galileo Ferraris published rotating-field experiments in 1888 from earlier Turin work. Sharing priority of the physical idea is not a reason to drop Tesla’s U.S. instrument.

Nikola Tesla is not the sole author of every later object, law, or museum label that uses the name. Shared work with courts, excavators, printers, spouses, officials, and later states does not erase a documented role, and it does not make an ancient person the signer of a twentieth-century statute.

## Evidence and sources

The patent text is a federal instrument. IEEE/ETHW independently treats the 1888 motor patents as Tesla’s core industrial contribution.

Official or archival record: U.S. Patent 381,968 — Electro Magnetic Motor (1888) (https://patents.google.com/patent/US381968A; United States Patent and Trademark Office / Google Patents).

## Significance

High confidence on the U.S. patent; medium on uniqueness against Ferraris.

Ferraris is not a rumour. Store the U.S. patent without erasing Turin.

## What is established and what is not

Established: U.S. Patent 381,968 on 1 May 1888 to Tesla. Not established: that he uniquely invented the rotating field in all jurisdictions, or that household electrification was already complete.

What would change the picture: a contradictory original with a different date or name, or a measured series that can be argued, with lag and alternatives, as a consequence of this instrument rather than of later institutions.

The date is the date of this instrument, not a licence to back-date every later harm or benefit.
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## People

- Nikola Tesla: https://factrail.ai/people/nikola-tesla

## Drivers

- Energy Security: https://factrail.ai/drivers/energy-security

## Sources

- https://patents.google.com/patent/US381968A
- https://ethw.org/Nikola_Tesla

## Methodology

https://factrail.ai/methodology

Canonical: https://factrail.ai/facts/us-tesla-patent-381968-1888