Nikola Tesla: Electro-Magnetic Motor, US Patent 381,968

Edition

Scan of the printed patent linked from Google Patents (https://patentimages.storage.googleapis.com/c9/47/b2/d2a511b818d8a6/US381968.pdf, 1-bit, 300 dpi, nine pages). Its first four pages, the sheets of drawings, are set side by side in the image at the top, each cropped to the drawing, its heading and its signatures (the scanner’s borders are left out) and kept in black and white. The specification (pages 1 to 5) is transcribed in full, word for word from the scan: an OCR made for this poster (RapidOCR) served as a base, every line was read against the page images, and the text was then compared by script with the OCR of Google Patents, each disagreement being settled on the scan. The printed heading (“UNITED STATES PATENT OFFICE.” / “NIKOLA TESLA, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO CHARLES F. PECK, OF ENGLEWOOD, NEW JERSEY.” / “ELECTRO-MAGNETIC MOTOR.” / “SPECIFICATION forming part of Letters Patent No. 381,968, dated May 1, 1888.” / “Application filed October 12, 1887. Serial No. 252,132. (No model.)”) is set in the header of the poster. Normalizations: words divided at line ends are rejoined without their hyphen, except in compounds divided at their own hyphen (generator-coils, three-quarters, contact-rings, generator-ring, alternating-current, field-magnet, circuit-connections, generator-shaft, energizing-coils); two words divided at a line end without a printed hyphen (“posi / tion”, “effect / ively”) are rejoined; the running heads, page numbers and the line numbers of the margins are dropped; the spacing of tightly set lines is normalized (as in “E E′” and “field-magnet”, set “field - magnet” once); the reference letters set in italics in the print are in italics, their primes and seconds are prime signs, and the superior letters of the figure numbers (1ᵃ to 8ᵃ) are superscripts. A damaged word read “typic..” on the scan is given as “typical”. The wording of the print is kept, including “the generator C′ C′ of the motor”, “to these of the motor”, “in side of the field-magnet” and “electro magnet” without a hyphen. Small capitals are kept for the inventor’s name in the preamble and for the witnesses. The caption of the drawings is not a period text: it was written for this poster from the specification.

Rights

US Patent 381,968 was granted to Nikola Tesla on 1 May 1888 and printed by the United States Patent Office. In the United States, it was published before 1931, and patents are publications of the federal government. In France, its author died on 7 January 1943, before 1 January 1956 (Wikidata Q9036), so the term of protection has expired.

The USPTO states: “Subject to limited exceptions reflected in 37 CFR 1.71(d) & (e) and 1.84(s), the text and drawings of a patent are typically not subject to copyright restrictions.” (https://www.uspto.gov/terms-use-uspto-websites, section “Patent information”, retrieved 2026-09-27.)