Patent · 1891 · age 35

US Patent 447921

Kept from patents.google.com · 2 files · 599 KBCall number TES PT1891.03

Provenance

Source: patents.google.comalso patentimages.storage.googleapis.com
Retrieved: 1 October 2026
Source terms (summary): Google terms: automated access against robots.txt counts as abuse
Rights: Public domainPatent text by Tesla, who died in 1943.Basis: author death year 1943, under a life-plus-70-years rule, as of 2026; other rules, such as the United States publication-date rules, are not assessed.
Formats: HTML, PDF scan
Fingerprint: 409e3aca31110d01f12c9451fb6166795c3ee26dfcb0fdfc5e42f0ce958d5073sha256 of the file (64 characters). Any change to the file changes this code.
Cite as: Nikola Tesla, US Patent 447921 (1891). Long Keeping, call number TES PT1891.03. https://longkeeping.com/nikola-tesla/us-patent-447921/

Unchanged since collected At the last check, on 2 October 2026, all 903 originals, this work's 2 files among them, matched the fingerprints recorded when they were collected. Each copy is re-checked by hand once a year; there is no automatic alert yet.

Notes on this copy

#1The file carries images, and no check is recorded yet that none of them is a picture of the person (the collection keeps no likenesses).
#2Machine-read text (OCR), not proofread, with no page images in the file to check it against.

Original

googlepatents_US447921A.html

Open reading copy 82 KB Exact filePublic domain

Reading copy: the saved page with its pictures left out. A picture appears in the reading copy only once the library has recorded its licence, the licence is on the library's pass list, and it has been checked for a likeness. See its pictures at the source (another site). Exact file: the page byte for byte; its pictures do not load here.

Files

First pass, not a clearance.

Links inside these saved pages were written for the site they were saved from; some lead nowhere here.

File	Format	Size	Source	sha256	Label
googlepatents_US447921A.html exact filemain	HTML	82 KB	patents.google.com	409e3aca31110d01f12c9451fb6166795c3ee26dfcb0fdfc5e42f0ce958d5073	Public domainPatent text by Tesla, who died in 1943.Basis: author death year 1943, under a life-plus-70-years rule, as of 2026; other rules, such as the United States publication-date rules, are not assessed.
googlepatents_US447921A_scan.pdf	PDF scan	517 KB	patentimages.storage.googleapis.com	4b171342c7ae7b0d34fd339d7562e5a6a8f191eea3a2fcb29c8b70f56c8386a0	Public domainPatent text by Tesla, who died in 1943.Basis: author death year 1943, under a life-plus-70-years rule, as of 2026; other rules, such as the United States publication-date rules, are not assessed.Held in the archive: its images await the archive's likeness review. Its source (another site)