US 278719

I'll run searches against public patent records and Federal Circuit docket sources for the literal identifier 278719.

Search results — literal identifier 278719

Searches performed: Google Patents full text (provided as the authoritative source), USPTO-oriented web queries, and Federal Circuit 2026 docket queries for "278719" / "278,719".

Findings on the CAFC/USPTO docket question:

• No Federal Circuit 2026 docket activity for patent 278719 was found. The only 2026 Federal Circuit hits that surfaced were non‑matches: ASSA ABLOY AB v. CPC Patent Technologies PTY Ltd, Nos. 25‑1078/1079/1080 (Fed. Cir. July 15, 2026), which concerns U.S. Patent Nos. 9,665,705 and 9,269,208 and a prior‑art reference named Mathiassen (a finger‑tap control), not patent 278719; and McRO, Inc. v. Bandai Namco Games (the '278 patent = U.S. 6,611,278), a seven‑digit number that is not 278719.
• This is consistent with the record: US278719 expired on 1900‑06‑05 (Google Patents legal status: "Expired – Lifetime"), so it cannot be the subject of a 2026 appeal.
• I did not retrieve a live USPTO PatentCenter/PAIR record page itself; the authoritative data below comes from the Google Patents full‑text record for US278719 at https://patents.google.com/patent/US278719/en.

Summary of US Patent 278,719

⚠️ Identifier caution: The Google Patents landing page renders the title field as "mathisen" (the inventor's surname, an artifact of OCR/indexing). The actual title in the printed specification is "DOOR-LOCK." I have not "corrected" the identifier — 278719 is treated literally as US278719A throughout.

Abstract

There is no abstract. Abstracts were not required or published for U.S. patents of this era. The closest equivalent is the stated object:

"My invention relates to an improvement in combined door lock and latch, the object of the same being to provide a device of this character which will combine simplicity, economy, and neatness in construction with durability and efficiency in use…"

Overview (as disclosed)

A rim‑mounted combined lock and latch: the lock‑case is recessed into the outer face of the door, retained by a single screw through the escutcheon on the inside, so it cannot be removed from outside. The knob‑shaft turns in hollow tubular bearings fixed between inward projections of the two case plates, taking all wear off the shaft and door; the bolt‑arm on the shaft plays between those projections. Knobs attach via sockets with conical screw pins that can be re‑tightened as they wear. The latch/bolt is spring‑projected and withdrawn through a link with knife‑edge lugs bearing on a partition of the bolt. Two optional locking arrangements are described: a key‑operated dog in a separable key‑housing, and a lock‑out pin passed through the bearing into a hole in the shaft. An adjustable two‑piece lock‑strike slides to fit the bolt regardless of door thickness. Figs. 8–12 show a modified form with a vertically moving latch for narrow door stiles.

Plain‑language reading of the claims

All seven claims are drafted in the single‑sentence "combination" style typical of 1883 practice. Statutory independent/dependent claim distinctions did not exist in 1883, so I note explicitly that I am not classifying any claim as dependent; all seven read as standalone combination claims, though claims 3–5 build on elements introduced in claims 1–2.

Claim 1 — A lock‑case with inward projections (a, a′) having tubular bearings fixed to opposite sides; combined with a knob‑shaft that turns in those tubes, and a bolt‑arm that plays between the projections. Core point: the shaft is journaled in tubes, not in the door.

Claim 2 — The knob‑shaft combined with knobs set at right angles to the shaft and socketed to receive its ends, secured by conical screws running lengthwise through the knobs and shaft ends. Core point: taper‑pin knob attachment that can be re‑tightened.

Claim 3 — The knob‑shaft and bolt‑arm combined with the latch/bolt (f) having lug e′, the link (e) having lugs e′/e″, and spring‑rods c, c′ with their springs. Core point: the link‑and‑lug spring latch train.

Claim 4 — The knob‑shaft (or bolt‑arm) combined with a latch/bolt having an oblong slot to receive the bolt‑arm's end, plus the link (e) engaged by that arm. Core point: the slot permitting latch retraction independent of the knobs when the door closes.

Claim 5 — The bolt (f), link (e), arm (a) and shaft (a′) combined with the key‑housing (h), plate (h²?), and dog (h³). Core point: the removable/separable key‑operated dogging mechanism.

Claim 6 — A lock combined with a lock‑strike made of an inner and an outer piece, the inner sliding under the outer to adjust for the latch/bolt. Core point: adjustability to door/latch thickness.

Claim 7 — In a lock‑strike, part p (with screw holes) combined with adjustable part p′ (with oblong screw openings), p′ sliding under p. Core point: the specific slotted, friction‑held slide adjustment.

Uncertainties / caveats

1. OCR corruption of reference characters (flagged, not corrected): In the source text the letters "e" and "c" and "o" are inconsistently rendered (e.g., "look" for "lock," "easing" for "casing," "0" for "e"), and claim 5's "plate 715" is clearly a mangled "h²"‑type character. My naming of claim elements above follows the description's clearer passages; the exact subscript assignment for the claim‑5 plate is not recoverable with certainty from the OCR.
2. No assignee appears anywhere in the record — I state that as the absence of data, not as confirmation that no assignment ever existed.
3. No CAFC docket record exists for 278719; the 2026 "Mathiassen" case is an unrelated prior‑art reference. I could not verify a live USPTO PAIR entry in this session and do not claim to have done so.

I'll search for litigation records involving US patent 278719.

Let me run additional targeted searches, including the Unified Patents litigation portal.

Litigation Search — U.S. Patent No. 278,719

Bottom line: No litigation involving U.S. Patent No. 278,719 is known or discoverable. I found no case — in federal district courts, the Court of Appeals for the Federal Circuit, PACER-based aggregators, the Unified Patents litigation portal, or any other database I could reach — in which U.S. Patent No. 278,719 was asserted, challenged, or otherwise at issue.

1. The patent at issue (verified against the full text)

For completeness: the only "citing" reference on the patent's face is US 2,500,849 (Everett S. Menns, "Window construction," filed Jan. 10, 1946, issued Mar. 14, 1950). A citation on the face of a patent is prior-art/classification citation activity — it is not litigation, and the Menns patent was filed 63 years after the Mathisen patent granted.

2. What I searched, and why the negative result is reliable

I ran targeted queries for the literal number 278719 and for variants including "278,719", patent 278719 litigation, 278719 infringement lawsuit, Mathisen door lock 1883 infringement, and a site-restricted query against portal.unifiedpatents.com.

Every nominal "hit" was a false positive on the string, not on the patent. Specifically, I encountered and discarded the following, none of which involve US 278,719:

• U.S. Patent No. 8,032,278 ("the '278 patent") — the Omega Patents, LLC v. CalAmp Corp. / Innova reexamination and IPR family (M.D. Fla., No. 6:13-cv-01950). This is a different patent (a vehicle telematics patent), and the ".278" collision is a common search trap.
• U.S. Patent No. 6,611,740 and related reexamination filings (Control No. 90/014,309) — same Omega/Innova family, unrelated to 278,719.
• California State Bar No. 278719 (attorney Hillary Bunsow, Bunsow De Mory LLP) — appearing in VideoLabs, Inc. v. HP Inc. (W.D. Tex. No. 6:23-cv-00641), In re Motion of VideoLabs, Inc. (N.D. Cal. No. 5:25-mc-80039), and Daedalus Blue, LLC v. MicroStrategy Inc. (E.D. Va. No. 2:20-cv-00551). This is a bar registration number, not a patent.
• Russian arbitration case No. А40-278719/2021 — a Moscow commercial case with no U.S. patent nexus.
• Spanish mercantile registry entry 278719 (SAL VESTA IBERIA SL) and a US Biological catalog no. USB-278719 (Hordenine reagent). Commercial/catalog numbers.
• U.S. Patent No. 4,198,656 (Mathisen) — a surname coincidence only; a 1980 video signal patent by a different Mathisen, not the 1883 door lock.

Additionally, the patent's own Google Patents page shows the "Similar Documents" and "Cited By" sections containing only patent documents (e.g., US 235,983; US 188,308; US 258,431; US 250,0849) with no litigation field populated. For a patent of this vintage, that absence is expected and is consistent with my searches.

3. Case list

No cases to report.

4. Why there is almost certainly no discoverable litigation — and the caveats you should weigh

1. The statutory term expired on June 5, 1900 (17 years from grant, pre-1995 term rules). Any infringement suit could only have been filed between June 1883 and June 1900.
2. Pre-1900 federal patent suits are not in modern dockets. PACER/CM-ECF coverage is generally limited to the late 1980s forward. Circuit Court equity cases from the 1880s–1890s survive principally as published opinions in the old Federal Reporter (1st series) and as National Archives records; they are not systematically indexed in Docket Alarm, Unified Patents' litigation portal, Lex Machina, or CourtListener's RECAP.
3. I could not run a full Westlaw/Lexis key-cite or a direct PACER query — both are paywalled and I cannot authenticate to them. My negative finding is therefore based on open-web and open-portal searching, which is comprehensive for post-1990 dockets and for published opinions, but is not a substitute for a Westlaw KeyCite "litigation history" report or a National Archives pull of the old Circuit Court equity dockets.
4. The inventor was Norwegian, and the invention was patented first in Belgium (Nov. 1881) and Norway. If any enforcement activity ever existed, the more likely forum would be European (Norway, Belgium, France, England, Italy, Portugal — see the counterpart list), and 19th-century European enforcement records are also largely undigitized.
5. I am not asserting affirmatively that no suit was ever filed in 1883–1900. I am stating that no such suit is discoverable through the sources available to me, and that the strong presumption is against any significant or reported litigation given the patent's age, the short remaining term, and its minor mechanical subject matter.

5. Recommended next steps if you need a litigation-grade answer

• Run a Westlaw KeyCite or Lexis Shepard's report on U.S. Patent No. 278,719 for the "Litigation History" / "Citing References – Cases" fields.
• Request a PACER docket search across all districts for the acronym "278719" and for "278,719" (though PACER coverage will not reach the 1883–1900 window).
• For the historic window, query the National Archives (NARA) for Circuit Court equity dockets, 1883–1900, and search the Federal Reporter (1st series) and Howell's / Macomber's patent digest compilations (the 1909 Macomber volume surfaced in my search and is a standard index of pre-1900 patent litigation).
• Contact the Norwegian Industrial Property Office (Patentstyret) and the Norwegian National Archives (Arkivverket) for enforcement records on Norway Patent Nov. 22, 1881.

Summary in one line: No litigation is known for U.S. Patent No. 278,719; the number collides with several unrelated modern identifiers (Bar No. 278719, US 8,032,278, Russian case А40-278719/2021), none of which is this patent.

I'll verify the structured data against public sources before drafting.

Searching once more with different phrasing to rule out any proceeding on this specific patent.

Proceedings overview

Total AIA trial proceedings on US 278,719: zero. There are no inter partes reviews, no post-grant reviews, and no covered business method reviews on file — the USPTO ODP "PTAB proceedings on file" block returns an empty set, and my searches (US 278,719 + IPR/PTAB, PTAB E2E, "Patent No. 278,719") surfaced no proceeding, no FWD, and no Federal Circuit appeal for this patent. The breakdown is therefore active / invalidated / sustained / settled / institution-denied = 0 / 0 / 0 / 0 / 0.

The defensive posture this gives a defendant is not "the patent is hardened" — it is that there is nothing to defend against. US 278,719 (Johan Mathisen, "Door-Lock," application filed 1882-10-09, issued 1883-06-05) reached its anticipated expiration on 1900-06-05, per the structured bibliographic data (Status: Expired - Lifetime). Its claims 1–7 have been in the public domain for roughly 126 years. Any demand letter citing US 278,719 as a basis for infringement liability is not a licensing overture; it is a document that can be used against its sender.

Proceedings

None. There is no proceeding to report, and I will not manufacture one. The section format below is retained only to document the negative findings and the legal reasons for them.

No proceeding on file — why this is the expected (and unavoidable) result

• Type: N/A
• Filed: N/A
• Status: N/A — the structured data shows the patent itself as Expired - Lifetime, with the legal-status event Anticipated expiration dated 1900-06-05.
• Judge panel: N/A
• Petition grounds: N/A

Rather than guess at claim-level outcomes, here is the reason no such outcomes exist:

1. Term. The patent issued 1883-06-05 and expired 1900-06-05 (17-year term, the rule at the time). AIA trials are creatures of the Leahy-Smith America Invents Act, with IPR/PGR/CBM available only from 2012-09-16 forward. Every AIA trial postdates this patent's expiration by more than 111 years.
2. PGR is categorically unavailable. 35 U.S.C. § 321(a) and § 122 require a post-grant review petition to target a patent "that contains or contained at any time a claim having an effective filing date" on or after 2013-03-16. US 278,719's effective filing date is 1882. This is a statutory impossibility, not a judgment call.
3. CBM is categorically unavailable and sunset. The Section 18 transitional program expired 2020-09-16, and it applied only to covered business method patents directed to financial products or services. A mechanical door lock classified in E05B 55/00 (locks in which a sliding latch also serves as a locking bolt) and Y10T292/Y10T70 is not a covered business method patent.
4. IPR is theoretically possible but practically void. IPR under § 311 is not restricted by patent filing date, so nothing in § 311 itself would bar a petition against an expired patent. But the Board's trial practice presumes a live controversy over enforceable claims, and an expired patent's claims cannot be infringed — there is no liability to extinguish, no royalty to defend, and no petitioner or patent owner with anything to gain. It is unsurprising that none was ever filed, and none appears in the ODP data.
5. Corroborating signals in the record. The Google Patents page for US 278,719 lists a single backward-citation "Cited By" entry — US 2,500,849 (Everett S. Menns, Window construction, 1950) — and a "Similar Documents" list of 19th-century lock patents. There is no "Cited By" entry corresponding to any PTAB proceeding, and the cited-by field for PTAB work is where institution decisions and FWDs would surface. The only text-classification signal on the page is mechanical (E05B, Y10T292/096 spring-projected sliding bolts, Y10T70/5199 swinging-door locks). Nothing in the file history indicates post-issuance adversarial review.

• Settlement / termination: N/A — no proceeding existed to terminate.
• Appeal: None. There is no PTAB decision to appeal to the Court of Appeals for the Federal Circuit, so there is no CAFC docket number to give you. I checked; I found nothing, and I decline to invent one.
• Defensive value: Total. This is the rare case where the strongest defense requires no PTAB work at all. See the trap-flag immediately below — the practical risk is not that you lose an IPR on 278,719, it is that you or your adversary conflate it with a different, live "'278 patent."

⚠️ False-positive trap — do not let this enter your brief. In patent litigation practice, "the '278 patent" almost always refers to something else. My searches for "278 patent" IPR returned a dense, active PTAB history for U.S. Patent No. 8,032,278 to Omega Patents, LLC — including IPR2023-00504 and IPR2023-01162 (Petitioner Verizon Connect Inc. v. Omega Patents, LLC), in which the Board issued a Final Written Decision on 2025-01-28 holding all claims of the '278 Patent unpatentable under pre-AIA 35 U.S.C. § 103(a) over U.S. Patent No. 6,756,885 to Flick in view of U.S. Patent No. 6,606,561 to Flick; Omega filed a Request for Director Review on 2025-02-26 and a CAFC appeal (see the unopposed motion to stay, dated 2025-04-10, in the Federal Circuit appeal from IPR2023-00504). That is a completely different patent — an automotive telematics/vehicle-data-bus patent — and it has no connection to the 1883 Mathisen door lock. If you are being asserted against a "'278 patent," confirm whether it is US 8,032,278 (live, with a claim-killing FWD you should cite) or US 278,719 (dead since 1900). The seven-digit versus eight-digit formatting is the only thing separating them in a search string.

Strategic summary

Claim status for US 278,719: every claim is UNTESTED and every claim is UNENFORCEABLE — not because of IPR, but because of expiration. Claims 1–7 (the combination claim to the lock-case with inward projections a and a and tubular bearings; the knob/socket/conical-screw claim; the latch/link/spring-rod combination; the oblong-slot bolt claim; the housing h / plate h³ / dog h³ claim; and the two adjustable lock-strike claims) were never canceled by the Board and never sustained by the Board. They simply lapsed on 1900-06-05 with the expiry of the patent term. There are no "surviving claims" to list, and no "narrowed" claim set — narrowing through IPR is a phenomenon that postdates this patent by a century. The file's only forward-looking legal signals are the 1900-06-05 anticipated-expiration event and the Expired - Lifetime status field.

Estoppel landscape: not applicable, and that is the operative point. 35 U.S.C. § 315(e)(2) estoppel attaches to a petitioner that has obtained a final written decision. No petitioner exists here, so there is no estoppel, no privity chain, and no barred ground to work around. Conversely, there is also no IPR record to leverage — no FWD to cite as an admission, no institution decision burying the patent owner's claim-construction position. A defendant facing a demand letter over US 278,719 has no need for an IPR-based defense, because the § 282 / § 271 liability question never reaches the merits: an expired patent cannot be infringed, and lapsed claims cannot support ongoing royalties. If you are counsel, the correct grounds are patent-term-based non-liability plus, if the demand is made in bad faith, an inquiry into state-law and Rule 11 exposure for the sender.

Pattern signals: none to speak of, because there is no modern activity around this patent at all. No repeat petitioner — no petitioner at all. No patent-owner appellate aggressiveness — the patent owner entity "Johan Mathisen, of Christiania, Norway" expired with the term; there is no assignee of record in the ODP data, and the family block lists a single application (US278719D) with a single country entry (US). No defensive aggregator: Unified Patents has not filed anything on US 278,719, and it would have no reason to — an 1883 expired patent is a dust-bunny, not a troll portfolio asset. This is the profile of a model-era (the specification is marked "(Model)" — a filing-type artifact from before the 1880s requirement to deposit physical models) mechanical lock patent that exists today purely as prior art, citation, and historical curiosity.

Recommended next steps

• If you are a defendant and a demand letter cites US 278,719: there is no FWD to link, because there is no FWD. Link instead to the authoritative bibliographic record at https://patents.google.com/patent/[US278719](/patent/US278719)/en, which states on its face: Prior art date 1883-06-05 and Anticipated expiration 1900-06-05, with Status: Expired - Lifetime. That single line is the whole defense. Consider quoting the status field directly into your response letter.
• Verify you have the right patent number. Before doing any of the above, confirm the asserted patent is US 278,719 (1883, Mathisen, door lock) and not US 8,032,278 (Omega Patents, vehicle telematics). If it is the latter, the picture inverts completely — you have a usable FWD (IPR2023-01162, Paper 34, 2025-01-28, all claims unpatentable under pre-AIA § 103(a) over Flick '885 + Flick '561) plus a companion proceeding, IPR2023-00504, with pending Director Review and CAFC appeals. Follow the appellate posture at CourtListener and the PTAB E2E docket before relying on either decision, since a pending Director Review can change the precedential effect.
• If active proceedings are pending on a different patent in your case: the ordinary PTAB milestones apply — the institution decision is due within six months of the petition's filing date (§ 314(b)), and the Final Written Decision is due within twelve months of institution (§ 316(a)(11)), extendable by six months for good cause. None of that has any application to US 278,719.
• Flat statement for the record: there is no PTAB activity on US 278,719, and there never will be. The absence here is not the usual "well-asserted patents eventually attract IPRs" signal, because the precondition for an IPR — a live, enforceable patent capable of being infringed — has been missing since 1900-06-05. Treat any assertion of this patent as a red flag about the sender, not as an infringement exposure.

Confidence note: I have high confidence in the negative finding and in the 1900-06-05 expiration date, both of which are grounded in the structured ODP data supplied in this prompt and corroborated by the Google Patents record. I found no evidence of any proceeding, and I found no contrary web results. I did not have access to a directly-queryable PTAB E2E or CourtListener docket for patent number 278,719, so if a proceeding were filed very recently it might not yet appear in indexed sources — but for the statutory and term-based reasons set out above, that possibility is functionally precluded.

I'll verify what's actually retrievable for this patent before writing the record.

US 278,719 — Ownership Reconstruction

Patent: US 278,719 — "Door-Lock." Issued 1883-06-05 to Johan Mathisen, Christiania, Kingdom of Norway. Application filed 1882-10-09 (Model). Executed/attested 1882-06-08. Foreign filings recited on the face: Belgium No. 56,159 (1881-11-15), Norway (1881-11-22), France No. 145,722 (1881-12-17), England No. 1,607 (1882-04-03), Portugal No. 769 (1882-08-22), Italy No. 14,424 (1882-09-30).

Search-execution caveat (read before relying on the timeline below). I could not drive the assignmentcenter.uspto.gov / assignment.uspto.gov UI programmatically in this session — it is a JavaScript-rendered application, and nothing in the accessible index surfaces any assignment record for this property. The "no records" finding below therefore rests on (a) the database's documented coverage start, (b) the independent Google Patents legal-events feed for US278719A, and (c) MPEP 301.01. It is a coverage-gap finding, not a claim-by-claim negative result from a manual Assignment Center query. A human should confirm with a direct query before any deal or opinion work.

Inventors

Pattern notes:

• Sole individual inventor, no corporate assignment. This is a pre-1880s-style Model patent granted to the inventor personally. The claims are drafted in first person ("what I claim as new"), and the attestation clause ("In testimony that I claim the foregoing I have hereunto set my hand this 8th day of June, 1882") is the inventor's own signature over witnesses Chr. S. Mauris and S. Bernhd. Asur — not a corporate officer's. There is no evidence of an employer-invention regime, and no basis to name one.
• The date cluster is a self-funded international filing program, not a corporate portfolio build. The Belgian and Norwegian filings (Nov 1881) predate the US filing by ~11 months, with French, British, Portuguese, and Italian counterparts following through 1882. That is the signature of an individual inventor raising his own foreign-filing budget to commercialize a lock in multiple markets — the opposite of the assignor-employee pattern (multiple co-inventors, one employer, a single US filing) that typically precedes a corporate portfolio transfer.
• No "all inventors departed within 12 months" signal applies — there is only one inventor and no assignee for him to depart from. Any inference of a subsequent fire-sale would require the pre-1980 paper record, which is not in the accessible dataset (see below).

Original assignee

None — no assignee is named on the issued patent. The patent issued to Johan Mathisen as the sole owner. This is confirmed by the Google Patents bibliographic record for US278719A, which lists no assignee field and shows only two legal events across the patent's entire life:

• 1883-06-05 — Application granted
• 1900-06-05 — Anticipated expiration (17-year term), legal status recorded as Expired – Lifetime

Because there is no assignee and no product record, the requested sub-findings do not apply: there is no primary line of business to state, no product embodying the claims that can be documented, and no current status beyond long expired (1900). Any claim that Mathisen sold a lock commercially, or that a Norwegian or other manufacturer took the patent, is not supported by anything I can verify — I am not going to infer a manufacturer from the drawings. The only commercial-inference datum is the multi-jurisdiction foreign filing set recited on the face of the patent, which indicates the inventor was actively seeking to exploit the invention in at least six countries.

Ownership inference: On this record, title presumably remained with Johan Mathisen or his estate throughout the term. The patent is public domain and has been since 1900-06-05; there is no subsisting ownership interest for anyone to assert.

Assignment timeline

There are no recorded assignments for US 278,719 in the USPTO Patent Assignment Search.

This is a coverage gap, not an affirmative "never assigned" finding, and the distinction matters:

1. The online database does not reach back to 1883. The USPTO's Patent Assignment Search (AOTW, now Assignment Center) "contains all recorded Patent Assignment information back to August 1980," per the USPTO's own assignment-database documentation. Bulk data confirms the boundary: the "Patent Assignment XML" dataset is explicitly scoped 1980-08-01 to present. US 278,719 issued 97 years before that window opens.
2. Pre-1980 records live in a separate silo that the website does not search. MPEP 301.01: "The historical database of assignments is maintained separate and apart from the database of assignments affecting title recorded since 1980." Post-1980 recordings are indexed by reel/frame with assignor, assignee, conveyance type, execution date, recording date, and correspondent of record. Historical records are not exposed that way online.
3. Even the paper record would be split across custodians. Under the rules reflected in MPEP 301.01, patent assignments recorded before May 1, 1957 are held by the National Archives and Records Administration (NARA), not the USPTO; recordings from 1957 to 1980 are retrievable from the USPTO's Assignment Recordation Branch by reel/frame on request. So an 1883–1900-era Mathisen assignment, if one exists, would be a microfilm reel/frame record obtainable only through the Assignment Recordation Branch or NARA — it would have no correspondent-of-record field, because the EPAS/correspondent indexing the review protocol depends on did not exist.
4. The Google Patents legal-events feed independently shows no assignment activity for US278719A — only the 1883 grant and the 1900 expiration.

Consequence for the brief you asked for: Because there are zero recorded assignments, there is no reel/frame, no conveyance type, no assignee, and no correspondent to log for any link in a chain. There is likewise no chain to diagram, and no basis to score shell-entity transfer, cascading transfers, pre-litigation transfer, privateering, or defensive aggregation. Per your protocol, I stop here rather than manufacture a chain.

⚠️ False-positive trap worth recording

A search for "278719" in modern USPTO systems returns US 3,872,019 (Lubrizol-type oil-soluble lubricant additives, filed 1972-08-08 as US application serial 278,719). That is a numeric collision between a 1972 modern application serial number and the 1883 patent number, unrelated to this patent in every respect. Google Patents itself propagates the confusion by minting an internal identifier US278719D for the 1883 grant. Anyone grepping "278719 / assignment" across databases will pull the 1970s family — do not let that contaminate an ownership chain for the Mathisen lock.

Verification links

• USPTO Assignment Center (search by patent number): https://assignmentcenter.uspto.gov/
• Legacy Assignment Search (same records): https://assignment.uspto.gov/patent/index.html
• Patent document + legal events: https://patents.google.com/patent/[US278719](/patent/US278719)/en
• Coverage boundary confirmation: https://data.uspto.gov/bulkdata/datasets (Patent Assignment XML, 1980-08-01 → present)

Remaining sections (Timeline diagram; NPE / troll-pattern signals; Verdict) are omitted per your instruction to stop after the Assignment timeline when the Assignment Center returns no records for the property.

For completeness of expectation rather than as a scored finding: this patent has been expired since 1900-06-05, so it is incapable of supporting an infringement assertion in any forum, and no rational NPE acquisition exists for it. If the underlying question is portfolio-level (e.g., a modern entity marketing a "Mathisen portfolio"), the relevant instruments would be in the 1980+ online index under the modern entity's name — searchable by assignee and by correspondent — and will not surface under this patent number.

I'll search the USPTO-relevant records and citation data for US patent 278719, then examine each cited reference.

Let me verify the citation records for the specific patent and examine the pre-1883 references listed alongside it.

Prior-Art Analysis — U.S. Patent No. 278,719 ("Door-Lock," Johan Mathisen)

Bottom line up front

U.S. Patent No. 278,719 has no prior-art citations on its face. The Google Patents/USPTO record for US278719A (https://patents.google.com/patent/[US278719](/patent/US278719)/en) contains no "Patent Citations" section at all — the only citation-type entry in the record is a forward "Cited By" reference (US2500849A), which, being 63 years later, cannot anticipate 278,719 under 35 U.S.C. § 102. This is exactly what one expects of an 1883 "Model"-type patent: pre-1880s/1890s U.S. patents were granted essentially without examination against prior art, so no examiner-cited references exist.

Accordingly, there are zero references cited on the patent that could anticipate any of claims 1–7. What I can do is (a) dispose of the one citation the record does show, and (b) analyze the pre-filing-date references that the database algorithm has associated with 278,719 ("Similar Documents"), which are the practical candidate prior-art pool.

1. What the record for 278,719 actually contains

⚠️ Identifier collision to keep straight (literal, not corrected):

• US278719A = the 1883 Mathisen door-lock (this analysis).
• US278719A / "US278719" also appears as an application/serial number on the Google Patents family pages of US3872019A ("Oil-soluble lubricant bi-functional additives…," filed 1972-08-08) — the same string denotes a completely different 1973–74 chemical patent. Likewise US278719D, US27871972A, US278719DA appear as index artifacts. None of these is the door-lock.

2. The one citation of record: US2500849A — and why it is not § 102 prior art

Conclusion for § 102: US2500849A is not citable as anticipating art for any of claims 1–7.

3. The pre-filing-date candidates ("Similar Documents") — the real § 102 inquiry

Because the patent has no citations of record, the only references that could possibly anticipate are those in the algorithmic "Similar Documents" list whose dates precede the 278,719 filing date.

Critical date: U.S. application filed October 9, 1882 (specification signed June 8, 1882), granted June 5, 1883. Foreign priority was claimed from Belgium, Nov. 15, 1881, with counterparts in Norway (11/22/1881), France (12/17/1881), England (4/3/1882), Portugal (8/22/1882), Italy (9/30/1882). For pre-AIA § 102(a)/(b) purposes, the operative prior-art date is generally the U.S. filing date, Oct. 9, 1882 (absent perfected § 119 priority benefit), with a practical outer boundary of the earliest foreign date, ~Nov. 15, 1881.

3a. References that predate the 278,719 filing date (potentially citable)

3b. References that postdate 278,719 — cannot be § 102 art

The remainder of the "Similar Documents" list is dated after June 5, 1883 and is therefore irrelevant to anticipation (it is only useful as evidence of later-state-of-the-art/obviousness context, and even that is limited):

US 344,722 (1886); US 333,022 (1885); US 326,626 (1885); US 372,962 (1887); US 400,111 (1889); US 427,157 (1890); US 543,679 (1895); US 576,242 (1897); US 638,404 (1899); US 667,297 (1901); US 668,650 (1901); US 695,888 (1902); US 724,677 (1903); US 841,209 (1907); US 866,893 (1907); US 911,192 (1909); US 945,276 (1910); US 1,003,956 (1911); US 1,143,653 (1915). None can anticipate under § 102.

3c. A reference I located separately but which is not prior art

US 717,757 — Combined lock and latch — discloses a locking-dog E operated by key-spindles, knobs with shanks, and a bayonet-joint — i.e., structurally close to 278,719's claim 5 (housing h/plate/dog). However, US 717,757 issues in 1902, nineteen years after 278,719. It is therefore not § 102 prior art against 278,719 (it would, conversely, be anticipated by 278,719).

4. § 102 framework applied to 278,719

1. Pre-AIA § 102 governs (application filed 1882). Anticipation requires a single reference disclosing every element of the claim, arranged as claimed.
2. Critical date: Oct. 9, 1882 (U.S. filing); earliest foreign date Nov. 15, 1881 if § 119 priority is perfected.
3. No cited art of record exists, so there is no examiner § 102 rejection to analyze; the analysis is purely reconstructive.
4. Claim-by-claim exposure to the pre-1882 pool (highest to lowest):
   • Claim 5 (key-housing/key-guard/dog) — most exposed; key-operated latch-dogging was well known before 1882 (e.g., the Batt US 235,983 concept of a key-actuated element locking the latch).
   • Claims 3 & 4 (link/lug/spring-rod train; oblong slot & link engaged by the arm) — moderately exposed; US 235,983 A's "drop-plate O … connecting the spindle with the latch" is the nearest pre-1882 analogue, though it lacks the specific knife-edge lugs e′/e″ and partition e³ and the oblong slot.
   • Claim 1 (shaft journaled in tubular bearings fixed to inward projections a, a′) and Claim 2 (socketed knobs with conical screws) — least exposed; these appear to be the points of novelty and I found no pre-1882 reference in the record disclosing them.
   • Claims 6 & 7 (two-piece adjustable lock-strike, inner piece p′ sliding under outer p with oblong screw slots) — no pre-1882 reference to these appears in the citation/similarity record at all.
5. Caveat on "anticipation" vs. "similarity": the references in §3a are listed as similar documents, not as citations of record, and I have full text for US 235,983 A only. For the others I have verified dates and titles but not their complete disclosures; whether any of them discloses all elements of a given claim cannot be asserted with high confidence without pulling each specification.

5. Explicit limitations of this analysis

• I could not open a live USPTO PatentCenter/PAIR record for 278,719 in this session; the citation data comes from the authoritative Google Patents full-text record (https://patents.google.com/patent/US278719/en), corroborated for the Menns citation via the FreePatentsOnline record for US2500849 (https://www.free PatentsOnline.com/2500849.html).
• "Similar Documents" ≠ citations. They are not part of the patent's prior-art record and are not § 102 art merely by being listed.
• No correction of identifiers was applied. 278719, US278719A, US278719D, US278719DA, and the serial-number US278719A appearing on the US3872019A family are all reported literally; the door-lock is US278719A (1883).
• If the requester intended a different patent whose number contains "278719" (e.g., US 2,787,785 was surfaced by search; US 8,032,278; US 6,611,278), that would materially change the art list — please confirm, because the literal 278719 maps only to the 1883 Mathisen door-lock.

One-line summary

No prior-art reference is cited on the face of US 278,719; its only citation of record (US2500849A, Menns 1950) is a forward citation that legally cannot anticipate it, and among the pre-filing-date documents associated with it (led by US 235,983 A, Batt, Dec. 28, 1880), only claims 3–5 even have arguable § 102 exposure — claims 1, 2, 6 and 7 appear unanticipated in the available record.

I'll gather what I can on the reference list actually present on this record before analyzing.

Obviousness Analysis — U.S. Patent No. 278,719 (Mathisen, "Door-Lock"), 35 U.S.C. § 103

A. Threshold qualifications you should weigh before reading the analysis

1. The premise of the request does not match the record. The fetched Google Patents page for US278719 (https://patents.google.com/patent/US278719/en) contains no "Prior Art" reference section. What it actually contains is: (a) a five-word "Prior art keywords" field (lock, door, bolt, knob, shaft); (b) a "Similar Documents" list of 20 U.S. patents; and (c) a single "Cited By" entry (US2500849A, Menns, 1950). I have treated (a)–(c) literally, flagged the "Cited By" item as a forward citation (post-dates 278719 by 67 years and is categorically not prior art), and supplemented with art retrieved by search. This is flagged rather than silently "corrected," per the operating rules.

2. § 103 did not exist when this patent issued. US278719 issued June 5, 1883 — 69 years before the Patent Act of 1952 created statutory obviousness. The 1883 statute (R.S. § 4886) was an anticipation statute ("not known or used by others... not patented or described in any printed publication"). The obviousness inquiry was instead the judge-made "want of invention" / "ordinary mechanical skill" doctrine, and the related "aggregation vs. combination" and "double use" doctrines. I therefore run the § 103 analysis as an explicitly counterfactual/hypothetical inquiry, but I use the pre-1952 doctrinal vocabulary where it is more faithful to how these claims would actually have been attacked.

3. Governing date law is pre-AIA. The critical date for invention is Mathisen's execution date, June 8, 1882 (specification attestation), with a filing date of October 9, 1882. Pre-AIA § 102 governs, and pre-AIA § 103 permits swearing behind a reference whose effective date falls between the inventor's actual invention date and the filing date (37 C.F.R. § 1.131). That matters here — see § B.3.

B. The reference set, sorted literally by date

B.1 List items that actually pre-date the critical date (potential prior art)

B.2 List items that post-date the critical date — background only, not prior art

US 326,626 (1885); US 333,022 (1885); US 344,722 (1886); US 372,962 (1887); US 400,111 (1889); US 427,157 (1890); US 543,679 (1895); US 576,242 (1897); US 638,404 (1899); US 667,297 (1901); US 695,888 (1902); US 724,677 (1903); US 841,209 (1907); US 866,893 (1907); US 911,192 (1909); US 945,276 (1910); US 1,003,956 (1911); US 1,143,653 (1915); and US 2,500,849 (Menns, 1950 — the "Cited By" entry).

Analytical consequence: roughly 18 of the 20 documents the page offers as "Similar Documents" cannot be used in a § 103 combination against these claims. An examiner or challenger working only from the page's own list has four usable references (47,470; 144,931; 188,308; 235,983) plus one that is close-dated and two that are unretrieved.

B.3 Supplementary art found by search — flagged as outside the record

• US 266,758 (Bridewell, San Francisco; filed March 29, 1882, issued Oct. 31, 1882), "Combined Lock and Latch": lock-frame with "two extensions B... made tubular" on its rear edge, and a knob-barrel D with projections E driving a flexible strap to the bolt, with a pivoted weight serving as the spring. https://patentimages.storage.googleapis.com/a6/4f/f3/a834086f96ca59/[US266758](/patent/US266758).pdf
  Timing trap: its issue date (Oct. 31, 1882) is after Mathisen's invention date (June 8, 1882), so under pre-1952 § 102 it is not prior art to Mathisen. Its filing date (Mar. 29, 1882) would make it prior art under AIA § 102(a)(2)/(d) — but the AIA does not govern an 1882 application. I include it only as evidence of the state of the art in the same year, not as a § 103 reference.
• US 136,723 (Hollemback, 1873), combined latch-and-lock with a night-lock operated by key; US 143,692 (Halsey, 1873), locking-latch with a key-operated night-lock "engaging with a shoulder on the latch to hold it locked." These corroborate the antiquity of key-operated dogging of a spring latch.
• State-of-the-art statement on knob attachment (from the Nashua Lock Co. litigation, reported at https://storage.courtlistener.com/harvard_pdf/[8164469](/patent/8164469).pdf): "The old form of connecting door-knobs to each other was by fastening the two knob shanks to the connecting spindle by side screws," with Niles' screwless shank patent of Dec. 12, 1882 following. This is contemporaneous judicial recognition that screw-fixed knob-to-spindle attachment was old and conventional.

B.4 The timing problem with the closest list reference

US 258,431 issued May 23, 1882; Mathisen's specification is executed June 8, 1882, and his earliest corresponding foreign filing is Belgium, Nov. 15, 1881. If Mathisen's actual reduction to practice tracks the Belgian/Norwegian filings, US 258,431 may be sworn behind under pre-AIA practice and drop out of the § 103 combination entirely. I cannot resolve this without the 1883 file wrapper, which is not in the record. This is the single biggest factual gap in any obviousness attack on this patent.

C. Claim-by-claim § 103 analysis

Recall from the prior section that all seven claims are single-sentence combination claims drafted in 1883 style, with no independent/dependent distinction. Also note a coverage gap worth flagging: Mathisen's most distinctive security feature — the single screw through the inside escutcheon so the lock cannot be removed from outside — appears only in the description and in no claim. The claims are directed entirely to (i) the bearing/shaft/arm architecture, (ii) knob attachment, (iii) the link-and-spring latch train, (iv) key-dogging, and (v)–(vii) the adjustable strike.

Claim 1 — two-plate case with inward projections a, a′; tubular bearings; shaft journaled in the tubes; bolt-arm playing between the projections

• Closest art: US 235,983 discloses a two-plate case with edge flanges and a spindle passing through it; US 266,758 (state-of-the-art only) shows tubular extensions formed on the lock frame and a knob-barrel; US 47,470 shows a knob-shaft passing through a lever-axle journalled in the case.
• Obviousness case: the remaining gap is the bearing tubes fixed between opposed inward projections of both plates, so that the shaft is journaled on the case rather than on the door wood. But providing a bushing/bearing for a rotating shaft was among the most elementary practices in mechanical art, and Mathisen's own specification supplies the motivation in the same breath as the claim: the tubes "take all the wear therefrom" and prevent "loose playing of the same through wear."
• Pre-1952 posture: this looks like an aggregation of a known case + known shaft + known bearing, producing no new coactive function — precisely the "every separate element... was old; the mechanical effect is precisely the same" reasoning the Supreme Court applied in the prison-door case surfaced in my search (Union Switch / jail-door line: "His motive was, and his use of the device was, to protect... but neither the motive nor the strength of the barrier can enter as an element into the question. The case is one merely of a double use.").
• Verdict: moderate–strong § 103 challenge, tempered by the fact that no retrieved reference shows the specific opposed-projection, double-tube journaling.

Claim 2 — knobs at right angles to the shaft, socketed to its ends, secured by conical screws passing longitudinally

• Closest art: the contemporaneous judicial statement above that side-screw knob-to-spindle attachment was the "old form"; and near-contemporaneous knob-attachment patents (Parker '820; Beebe '684 — both 1885, therefore background only).
• Obviousness case: this claim is a known attachment means applied to a known element, with the specification itself identifying the only asserted benefit — conical pins "can be screwed home as the parts wear away." Taking up wear with a taper pin is a staple of mechanical practice; substituting a taper fastener for a cylindrical one to obtain a take-up function is a predictable substitution of a known equivalent.
• Verdict: strongest § 103 challenge in the patent. This claim is also the most vulnerable to a pre-1952 "mere substitution of one well-known device for another" rejection, a rationale the Patent Office was using in this exact era ("The mere substitution of one well-known kind of locks for another kind equally well-known has been decided again and again as not a patentable difference" — examiner's rejection quoted in the Sargent time-lock litigation retrieved in my search).

Claim 3 — shaft + bolt-arm + latch f with lug e′ + link e with knife-edge lugs e′, e″ + spring-rods c, c′ and springs

• Closest art (the strongest single combination on this record): US 188,308 (Sherman) expressly solves the same problem Mathisen states — decoupling the latch from the knob train so the latch can move independently — through the tongue q and cross-pins that "determine the amount of motion, so that the latch can be operated upon by the key without moving the rack or handle." US 144,931 (Stowe) supplies the spring-biased element with a lug riding in a recess in the bolt to hold/release the bolt. US 235,983 supplies the spring-projected latch plus an apertured connector actuated by the knob-spindle.
• Motivation to combine: identical field (rim/mortise spring latches), identical problem (independent latch/knob movement and self-latching on door closure), and a finite, identified set of solutions (a spring-biased floating link with lost motion). Mathisen's own stated object — "simplicity, economy... durability and efficiency" — is the kind of acknowledged design incentive that supplies motivation.
• Where the claim may survive: the specific recitation of **two inwardly extending knife-edge lugs resting on opposite sides of a partition of the bolt is a narrow structural detail; no retrieved reference shows opposed knife-edge lugs on a bolt partition.
• Verdict: moderate challenge; the strongest of the seven to defend on its literal recitation, though a court applying the era's narrow-construction rule to combination claims would confine it to the exact structure (cf. the coupler case retrieved in search: "It is a patent which, if valid at all, is entitled only to the narrowest construction, and any variation in any of the parts of the combination will prevent infringement").

Claim 4 — shaft/bolt-arm + latch with oblong slot receiving the bolt-arm + link e engaged by the arm

• Closest art: US 188,308 (Sherman) — slot-and-stop lost motion between latch and driver, with the very same stated advantage; US 235,983 — latch C slotted at its rear end to receive guide-pin D, and bolt E slotted on guide-pin F; US 144,931 (Stowe) — recess a cut into the bolt for lug d.
• Obviousness case: slot-and-pin lost motion is the paradigm predictable mechanical expedient, and Sherman not only discloses the structure but articulates the identical functional motivation.
• Verdict: strong § 103 challenge. Of the "train" claims (3–5), this one has the weakest structural specificity and the closest single-reference teaching.

Claim 5 — bolt f, link e, arm a, shaft a′ + key-housing h, plate h², dog h³

• Closest art: US 47,470 (Van der Veer) discloses a key-operated "traverse" dog that engages the spring latch to lock it and disengages to leave the latch acting as a spring latch — functionally identical dogging. US 235,983 discloses the same combination (key-operated bolt with slotted plate and spring, in a case also containing the spring latch and knob spindle). US 143,692 (Halsey) and US 136,723 (Hollemback) corroborate key-operated night-locks engaging the latch shoulder.
• Motivation to combine: the security problem (a knob-retractable latch is not a lock) drove this entire art; Van der Veer's Fig. 3 note that the dog is simply relocated "behind the latch-frame" for heavier doors is an express teaching that dog placement/mounting is a variable design choice.
• Where the claim may survive: the recitation of the key-housing, key-guards, and plate cast integral and secured by one screw as a removable sub-assembly. The specification supplies the motivation itself ("can be manufactured independent of the main lock, and... removed for repairs or replaced at pleasure"), which cuts both ways: modularity for repair is a recognized manufacturing desideratum, and KSR-style rationales treat design/repair-convenience incentives as motivations.
• Verdict: moderate challenge. The functional dogging is squarely old; the modular housing is a convenience feature.

Claims 6 & 7 — two-piece adjustable lock-strike (inner part sliding under outer; oblong screw slots; friction-held)

• Closest art in the record: none of the four usable list references shows an adjustable strike; US 188,308 shows only a bored strike case with a spring-and-button hole cover.
• Available support for adjustability being a known category: the USPTO's own classification of this patent places the strike in Y10T292/705 — "Keepers — Adjustable" (and Y10T292/68 "Keepers"), a dedicated subclass the Office maintains for adjustable keepers. My search also surfaced two 1857 "Improvements in Keepers for Locks and Latches" (US 17,611 Patterson; US 16,676 Adams, noted in the 1857 Commissioner's Annual Report), which confirm keeper/strike design as an independent, actively cultivated art by the 1850s–1880s.
• Obviousness case: the problem — the strike's bearing face must fit the bolt "irrespective of the thickness of the door-latch or lock-case" — is inherent in the fitment of every rim lock. A two-piece sliding plate with slotted screw holes is the conventional, predictable structure for any adjustable bracket; the claim adds nothing beyond ordinary sliding-plate adjustment mechanics, and claim 7's "friction-hold" is the natural consequence of driving screws through slots in a wood frame.
• Verdict: strong § 103 challenge, but weakest support on the record as fetched (I could not retrieve a pre-1882 adjustable-strike reference directly). A challenger would need to supplement with keeper art, which is readily available in the pre-1883 U.S. patent corpus.

Summary table

D. Why a person of ordinary skill would have combined these references

Stated in terms usable both under pre-1952 doctrine and under a modern § 103 challenge to these pre-AIA claims:

1. Same field, same problem — no analogous-art barrier. All four usable references are door locks/latches (two are literally titled "combined lock and latch"). The problem of a spring latch that self-latches on door closure yet can be retracted from either side, and can be locked against knob operation, is the shared subject matter of US 188,308, US 235,983, US 144,931 and US 47,470. Combining references within one recognized art, addressing one recognized problem, is the least controversial combination there is.
2. The references articulate Mathisen's own stated problems. Sherman: latch operable "without moving the rack or handle." US 235,983: latch "thrown into and out of gear with the spindle," lock "cannot be readily picked." Van der Veer: eliminate the separate lock portion so the latch "does the office of both." These are the same objectives Mathisen recites in his opening object clause.
3. Design incentives expressly acknowledged in the patent. Mathisen's stated object — "simplicity, economy, and neatness in construction with durability and efficiency in use" — is a recitation of ordinary design desiderata, and a challenger will argue that an inventor who states his goal as simplicity/economy/durability has supplied the motivation for using simpler, cheaper, more durable known mechanisms (bushings, taper pins, sliding plates).
4. A finite, predictable set of solutions. Spring-biased floating link with lost motion; taper fastener for take-up; two-piece sliding bracket — each is the standard answer to a well-known problem, in a crowded art (the page's own "Similar Documents" list alone shows ~20 U.S. patents in the same classification, E05B55/00 / Y10T292/096–0985).
5. Variable design parameters. Van der Veer's relocation of the dog "behind the latch-frame" for heavier doors shows the art treating dog mounting as an adjustable design choice, supporting claim 5.

E. Secondary considerations and evidentiary gaps

• No secondary-consideration evidence exists in this record: no commercial success, no long-felt but unmet need, no copying, no failure of others, no licensing. Mathisen's six foreign filings in 1881–82 (Belgium, Norway, France, England, Portugal, Italy) demonstrate the inventor sought broad protection; they are not evidence of nonobviousness.
• Independent validity flag not asked for but material: the Belgian (Nov. 15, 1881) and Norwegian (Nov. 22, 1881) grants both pre-date Mathisen's June 8, 1882 U.S. execution. Under pre-1952 R.S. § 4886, a foreign patent that was printed and published before the U.S. invention date could bear on patentability. This is worth checking against the foreign specifications before any challenge is mounted — it is flagged, not asserted, since I did not retrieve those documents.
• What I could not verify: (i) the 1883 Patent Office file wrapper, so I cannot say whether any of the "Similar Documents" were cited or overcome during prosecution, nor verify the "Model" prosecution history; (ii) the disclosures of US 258,431 and US 238,113 (both list items are relevant-date references and both were unretrievable); (iii) the drawings, which is where several claim limitations (knife-edge lugs e′, e″, the partition, the housing casting) actually live; (iv) any lived commercial history of the lock.

F. Bottom line

On the record as fetched, the patent is vulnerable across all seven claims, but the vulnerabilities differ in kind.

• Claims 2, 4, 6 and 7 are the weakest: claim 2 recites a conventional screw-fixed knob attachment and adds only a taper pin for wear take-up; claim 4 recites slot-and-pin lost motion that US 188,308 (Sherman, 1877) discloses together with the identical functional explanation; claims 6–7 recite a two-piece slotted sliding plate, the standard structure for any adjustable bracket and the very subject of the Office's own "Keepers — Adjustable" subclass.
• Claims 1, 3 and 5 are more resilient as literally drafted, because each contains a structural particularity not found in the retrieved art (opposed journal tubes between inward projections; two opposed knife-edge lugs on a partition; an integral, single-screw, removable key-housing sub-assembly). But under the pre-1952 rule that a combination claim of this vintage in a crowded art is entitled to the narrowest construction, that resilience is the same property that makes the claims easy to design around.
• The single most decisive open question is not obviousness at all — it is whether US 258,431 (May 23, 1882) and US 238,113 (Feb. 22, 1881) can be sworn behind or, conversely, whether they supply the missing link. Neither could be retrieved, and both are close to the critical date. Resolving them, plus pulling the 1883 file wrapper, should precede any formal § 103 position.