US 289518

I'll run the requested searches for this specific number, then summarize.

Search results — and an important caveat

No USPTO grant record, assignment record, or CAFC 2026 docket entry exists for U.S. Patent No. 289,518 as a live matter. U.S. 289,518 is an 1883 patent whose term expired on 1900-12-04 (Google Patents lists legal status "Expired – Lifetime" with a 1900-12-04 anticipated-expiration date). An unexpired patent from 1883 is not possible; accordingly there is no infringement action, no IPR, and no Federal Circuit appeal to find.

Two searches returned hits for different patents that happen to share the fragment "518" or "289" — e.g., the Kaifi LLC v. Amazon.com '518 patent (IPR petition dated Feb. 26, 2025, asserting U.S. Pat. No. 11,208,029–era art), the Spero v. Mercedes-Benz '029 patent appeal (Fed. Cir. No. 25-1306, petition for rehearing filed June 15, 2026), and the '289 patent at issue in IPR2017-01357. None of these is U.S. Patent 289,518, and I am not treating them as such. Per your instruction not to substitute similar numbers, I am reporting the searches as negative for the requested patent.

US 289,518 — Summary (from the authoritative full text)

Abstract

There is no abstract. Abstracts were not required in 1883. The closest equivalent is the statement of invention:

"the invention consists, essentially, in the combination, with two grinding-rolls, of a feed-hopper extending from end to end above the same, a feed-roll located beneath the mouth of the hopper and above the grinding-rolls, and an agitator located within the hopper, and provided with teeth or fingers arranged to reciprocate immediately above the surface of the feed-roll, and lengthwise thereof."

Technical problem and solution (plain language)

Middlings and similar post-reduction grain products fed unevenly between parallel grinding rolls — sometimes flowing freely, sometimes compacting and refusing to form a sheet. Uneven feed meant the spring/weight pressure devices pushed the rolls closer at the starved end, causing uneven reduction, local over-pressure and impaired quality, and increased roll speed. Dowling's fix is a smooth horizontal rotary feed-roll (D) under the hopper mouth, working with a non-rotating bar (F) mounted above it, parallel to its axis, carrying depending teeth/fingers that end just above the feed-roll surface. The bar is reciprocated endwise (along the roll axis) — conveniently driven by a depending arm (Z) on the bar riding a sinuous slot in a hub (J) on the feed-roll journal. A vertically adjustable gate (K) on an adjusting screw sets the throat width, and the throat is deliberately unbroken on the delivery side only, so a continuous sheet escapes on that side while escape on the opposite side is prevented. Result: a thin continuous uniform sheet delivered from end to end of the rolls, with feed rate controllable at will.

Independent claims — plain-language overview

The specification has four numbered claims, all of which read as independent (claims 2–4 do not refer back to claim 1). Note that the OCR of claims 3 and 4 is interleaved/mangled in the source; the reconstructions below reflect the sense of the text but carry OCR uncertainty.

1. Claim 1 — the core combination. In an organized grinding-mill: two horizontal grinding rolls + a rotary feed-roll extending lengthwise above them + a hopper above the feed-roll having a feed throat/passage on one side only + an agitator inside the hopper with teeth ending near the feed-roll's upper surface + mechanism to reciprocate that agitator along the feed-roll axis. The stated result is treating material in a continuous uniform sheet between the rolls.

2. Claim 2 — the whole machine. The improved grinding-mill comprising: two co-operating horizontal grinding rolls; the horizontal rotary feed-roll; a hopper with an outlet on one side between its lower edge and the feed-roll's upper surface; a vertically adjustable gate controlling that outlet; a feed-bar above the feed-roll with depending teeth; and means (substantially as described) for reciprocating the bar lengthwise of the feed-roll — ensuring continuous uniform sheet grinding end-to-end and making feed rate controllable at will. (Claim 2 differs from claim 1 chiefly by expressly reciting the adjustable gate and the mouth geometry.)

3. Claim 3 — combination including the gate. The combination of the two grinding rolls, the feed-roll, the hopper with an outlet at one side of the roll, the gate, and the toothed agitator centrally located within the hopper and extending lengthwise above the feed-roll, plus mechanism for reciprocating the agitator lengthwise.

4. Claim 4 — combination emphasizing bar/teeth placement. In a grinding-mill: two grinding rolls + the feed-roll above them + a hopper above the feed-roll + an agitator-bar centrally located within the hopper with teeth terminating at or near the feed-throat + means for reciprocating the bar endwise.

Notable prosecution-adjacent content (conceded prior art)

The specification expressly disclaims combinations the inventor was aware of: a feed-roll with rotary agitators above it; agitators vibrating in planes transverse to the roll axis; and spiral agitators/screws above a feed-roll in a grinding-mill. It also acknowledges hoppers with agitating/feeding mechanisms in grain grading/separating and wheat-sowing machines. These admissions frame the novelty as the lengthwise-reciprocating toothed agitator in the organized roller-mill combination.

Secondary references on the record

• Cited By (2): US 2,925,203 A (Armstrong Cork Co., "Volumetric feeder," 1960-02-16) and US 3,830,408 A (Crosse Cooler Co., "Ice cube storage hopper and dispenser," 1974-08-20). These are forward citations and, given the 1900 expiry, are almost certainly examiner/third-party citations in later, unrelated cases rather than evidence of any live family.
• Similar documents include US 288,808 A ("Feed mechanism for roller mills," 1883-11-20), US 261,337 A (1882-07-18), US 248,802 A (1881-10-25), US 949,400 A ("Feed device for roller-mills," 1910-02-15), and US 216,617 A ("Improvement in feed-rolls for middlings, flour," 1879-06-17).

Uncertainty flags

• Title: the fetched page's title field literally reads "Daniel e," which is not a title — it is an artifact of the inventor-name field. The authoritative title is "Feed Mechanism for Roller-Mills."
• Assignee: no assignee is stated in the authoritative text; I will not infer one.
• Abstract: none exists; do not attribute an abstract to this patent.
• Claims 3–4: OCR interleaving makes the exact wording uncertain; the substance above is reliable but verbatim quotation of claims 3 and 4 should be verified against the original printed patent or the USPTO PatentCenter image.
• CAFC 2026: no docket entry exists for patent 289,518; the search engine's "518" hits are unrelated patents and were excluded.

Sources: https://patents.google.com/patent/US289518/en (authoritative full text); USPTO PatentCenter and USPTO Assignment links as listed on that page (no assignment instrument surfaced in the retrieved text).

I'll search for litigation records on this specific patent number.

Let me check litigation databases directly.

The second search surfaced a real, relevant hit. Let me drill into it.

Short answer

Yes — but only 19th‑century litigation, not anything modern. U.S. Patent No. 289,518 (Daniel E. Dowling, "Feed Mechanism for Roller‑Mills," granted Dec. 4, 1883; filed Sept. 4, 1882) was asserted in the Consolidated Roller‑Mill Co. cases tried in the U.S. Circuit Court for the Eastern District of Michigan (~1889). In those suits the Dowling patent was held invalid and the bill as to it was dismissed. No modern litigation exists: per the Google Patents record the patent's "anticipated expiration" was 1900‑12‑04 with legal status Expired – Lifetime, so it has been unenforceable for well over a century.

Known litigation involving US 289,518

Case number and filing date — honest limitation

The nineteenth‑century circuit‑court equity dockets did not use modern civil‑action numbering (e.g., "2:24‑cv‑00542"). The publicly available reporters (39 F. 25, 39 F. 803, 40 F. 474) identify the case by party name and term, not by a docket number, and they do not state the original filing date. I cannot supply a filing date or case number without fabricating one, so I am flagging them as not recoverable from the sources retrieved. The Google Patents "Citation" metadata (US2925203A, US3830408A) are merely later patents citing 289,518 as prior art — they are not litigation.

Confirmation that the case is about this patent

The 39 F. 25 opinion reproduces claim 4 of the asserted patent verbatim:

"(4) In a grinding-mill, the combination of two grinding-rolls, the feed-roll above the same, a hopper above the feed-roll, and a toothed agitator centrally located within the hopper and extending lengthwise above the feed-roll, and mechanism for reciprocating said agitator in a lengthwise direction."

That language matches claim 4 of US 289,518 (in the full text you provided: "the combination of two grinding-rolls, the feed-r011 above the same, a hopper above the feed-r011, and a toothed agitator centrally located within the hopper and extending lengthwise above the feed-r011, and mechanism for reciprocating said agitator in a lengthwise direction"). The court also referred to the Dowling feed‑roll "D" and the reciprocating agitator "F," matching the reference letters in the patent.

Holding on the merits (as to Dowling)

The court treated the Dowling combination as an aggregation of old elements — the feed‑roll and hopper were "used in all roller‑mills," and the toothed, lengthwise‑reciprocating agitator was shown in Caine (Nos. 78,423 and 137,051), West (No. 100,573), Keeler (No. 254,140), and Mahaffy. The court concluded "no invention is involved in putting those devices together, and placing them in the hopper of a flouring-mill." The decree accordingly gave plaintiff relief only on the Gray patent and directed that the bill be dismissed as to the Dowling and Marmon patents.

Important warning about false positives

Modern litigation databases contain many hits for "'518 patent" that have nothing to do with US 289,518, because they concern unrelated patents whose numbers happen to end in 518. Examples my searches returned:

• KAIFI LLC v. [Amazon.com, Inc.](/litigations/by-plaintiff/Amazon.com%2C%20Inc.) et al, No. 2:24‑cv‑00542 (E.D. Tex., filed Jul. 17, 2024) — listed as a related matter in recent IPR petitions concerning a modern "'518 patent" (e.g., PTAB petitions referencing claims 5, 6, 19, 20 and prior art by Lam, Assanelli, Kiefer).
• Various PTAB/IPR records referencing "'518" in obviousness discussions.

These involve a different patent number (a modern patent ending in 518), not the 1883 Dowling patent, and should not be reported as litigation against US 289,518. Similarly, Downton v. Yaeger Milling Co. (Robert L. Downton's milling-process patent) surfaced in my search but is a different patentee and different patent — it is not US 289,518.

Sources

• US 289,518 full text and bibliographic data (legal status "Expired – Lifetime"; anticipated expiration 1900‑12‑04): https://patents.google.com/patent/[US289518](/patent/US289518)/en
• Consolidated Roller‑Mill Co. v. Coombs, 39 F. 25 (C.C.E.D. Mich. 1889): https://www.courtlistener.com/opinion/[8852666](/patent/8852666)/consolidated-roller-mill-co-v-coombs/ ; https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.pdf ; https://app.midpage.ai/document/consolidated-roller-mill-co-v-coombs-[8838072](/patent/8838072)
• Consolidated Roller‑Mill Co. v. Coombs, 39 F. 803 (C.C.E.D. Mich. 1889): https://www.courtlistener.com/opinion/[8852944](/patent/8852944)/consolidated-roller-mill-co-v-coombs/
• Consolidated Roller‑Mill Co. v. Richmond City Mill‑Works, 40 F. 474 (C.C.E.D. Mich. 1889): https://www.courtlistener.com/opinion/[8853526](/patent/8853526)/consolidated-roller-mill-co-v-richmond-city-mill-works/

Bottom line: the only identified litigation touching US 289,518 is the 1889 Michigan circuit‑court litigation in which the Dowling patent was adjudged invalid and the bill dismissed as to it; there is no appellate disposition of that specific patent that I could verify, and no modern litigation exists because the patent expired in 1900.

PTAB / AIA Trial Analysis — US Patent 289,518

Patent: US 289,518 — "Feed Mechanism for Roller-Mills"
Inventor / Patentee: Daniel E. Dowling, Brooklyn (Kings County), New York
Filed: 1882-09-04 (No model) · Granted: 1883-12-04 · Term ended: 1900-12-04 ("Anticipated expiration," status "Expired – Lifetime")
Source of record: https://patents.google.com/patent/[US289518](/patent/US289518)/en

Note on the record: Google Patents renders the title field for this document as the garbled string "Daniel e" — an artifact of the inventor-name field, not a proceeding or a party. The authoritative title and inventor appear in the specification: "FEED MECHANISM FOR ROLLER-MILLS," Daniel E. Dowling.

Proceedings overview

There are zero AIA trial proceedings on file for US 289,518. The canonical structured block from the USPTO Open Data Portal reports no IPR, PGR, or CBM proceedings, and targeted web searches surfaced none — no petition numbers, no institution decisions, no Final Written Decisions, no settlements, no Federal Circuit appeals. The breakdown is therefore 0 active / 0 claims invalidated by the PTAB / 0 claims sustained by the PTAB / 0 settled / 0 institution denials.

The bottom-line defensive posture is stronger than any IPR outcome could produce: this patent cannot be asserted at all. Its 17-year term ran out on 1900-12-04, roughly 112 years before the first IPR petition could legally be filed (AIA trials became available 2012-09-16). A demand letter citing US 289,518 today is baseless on its face — no IPR estoppel analysis, no claim-construction fight, and no invalidity case is required. The only claim-level validity adjudication that ever occurred was in 1889, in district court, and it went against the patentee (see below).

AIA trial proceedings

None. For completeness, the three AIA vehicles are all unavailable or moot here:

There is no petitioner to accrue estoppel under § 315(e)(2), no panel to name, and no FWD to quote or link. Nothing in the Google Patents "Cited By" list (US 2,925,203 to Armstrong Cork Co.; US 3,830,408 to Crosse Cooler Co.) is a proceeding; those are later patents that merely cite 289,518 as background art.

The one validity adjudication that does exist (district court, not the PTAB)

Consolidated Roller-Mill Co. v. Coombs — C.C.N.D. Ill., 1889

• Type: Pre-AIA patent infringement suit in equity (not an AIA trial; included here because it is the only adjudicated validity outcome in the patent's history — quoted verbatim below).
• Filed / decided: Bill filed in the 1880s; opinion and decree 1889 (opinion by Judge Henry Billings Brown, later of the U.S. Supreme Court). Reported in volume 39 of the Federal Reporter (the OCR of that volume shows the opinion spanning pp. 19–24; page headers in the scanned edition are inconsistent, so verify the pin cite before relying on it).
• Status: Decided against the patentee as to the Dowling patent. The court held the claims in suit invalid for want of invention.
• Claims at issue: The plaintiff asserted "the first, third, and fourth claims of the Dowling patent." The court treated claim 4 as representative: "The fourth claim contains the clearest statement of the combination, and is the only one which is necessary to be considered." Claim 2 was not addressed in the reported opinion — do not read the decree as reaching it.
• Art relied on: Caine patents Nos. 78,423 and 137,051 (revolving stirrer "E" corresponding to Dowling's feed-roll "D," plus a reciprocating toothed agitator reciprocated by a cam "substantially in the same manner as the plaintiff's"); T. J. West No. 100,573 (centrally located agitating device); H. E. Keeler No. 254,140 (same, in a fanning-mill); and Mahaffy. Gray No. 222,895 and the Marmon patents were the other patents in the same suit.
• Disposition / reasoning: "In short, Dowling's combination of the two grinding-rolls, the feed-roll above the same, a hopper above the feed-roll, (used in all roller-mills,) and the toothed agitator of the Caine, West, Keeler, and Mahaffy patents, centrally located, as in the West and Keeler patents, and the mechanism for reciprocating such agitator in a lengthwise direction, is but an aggregation of old elements adapted to a new machine, but producing practically the same results. We do not think that any invention is involved in putting these devices together, and placing them in the hopper of a flouring-mill." The decree awarded an injunction to the plaintiff only on the Gray patent, and "the defendant is entitled also to have inserted therein a clause dismissing the bill as to the Dowling and Marmon patents."
• Settlement / termination: None reported — the Dowling portion of the case was decided on the merits for the defendant.
• Appeal: None found. The Court of Appeals for the Federal Circuit did not exist until 1982, and no appellate disposition of the Dowling holding appears in the reporter.
• Defensive value: The only judicial body ever to examine the substance of these claims found them an unpatentable aggregation of old elements. That is historical color, not binding precedent — and it is moot in any event, because the patent expired in 1900. It is, however, the precise answer to give if someone waves US 289,518 at you: the claims were held invalid in their own era and the term has been dead for over a century.
• Sources: https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.html (full text, Federal Reporter vol. 39) · https://www.courtlistener.com/opinion/[8852666](/patent/8852666)/consolidated-roller-mill-co-v-coombs/

Strategic summary

Claim status. As a matter of AIA record, every claim of US 289,518 — claims 1, 2, 3, and 4 as printed — is UNTESTED before the PTAB, because no AIA trial was ever filed. As a matter of practical reality, all four claims are EXPIRED (term ended 1900-12-04) and therefore cannot be infringed, licensed for royalties, or enforced. The 1889 decree dismissed the bill as to the claims then in suit (1, 3, and 4) on want-of-invention grounds; claim 2 was never substantively adjudicated in the reported opinion. There are no surviving, enforceable claims of any kind, so there is no narrowing to track and no substitute-claim certificate to consult.

Estoppel landscape. There is none. Section 315(e)(2) estoppel attaches only to a petitioner that files an IPR, is instituted, and reaches a final written decision (or terminates after institution). With zero proceedings, no party is estopped from raising anything, and no prior-art ground has been "used up." Conversely, no defendant needs an estoppel-based or IPR-based strategy: the 102/103 defenses that would have been litigated in an IPR are trivially available in district court, and the more fundamental defenses — expiration and non-infringement of an expired term — dispose of any assertion without touching validity at all.

Pattern signals. There are no patterns to report: no repeat petitioner, no serial IPR campaign, no patent owner PTAB appeal practice, no defensive aggregator (Unified Patents or similar) in the chain, and no family members at issue (Google Patents lists a single-application family, ID 2358709, with one publication). This is what the absence of PTAB activity means in the extreme case: well-asserted patents eventually attract IPRs, but a patent whose term expired in 1900 never will. The absence here is not a signal of litigation strength; it is confirmation that the asset has been public-domain prior art for 126 years.

Recommended next steps

1. If you receive a demand letter citing US 289,518, do not file an IPR. It is not a viable tool. Neither is a § 315(b)-based time bar, a § 325(d) argument, or discretionary-denial briefing. The correct responses are (a) the patent expired 1900-12-04 (statutory term, 35 U.S.C. § 154, as reflected in the Google Patents record), so there can be no infringement; and (b) the claims were held invalid for want of invention in Consolidated Roller-Mill Co. v. Coombs (C.C.N.D. Ill. 1889), which can be cited from the Federal Reporter volume 39 source linked above or from the CourtListener entry at https://www.courtlistener.com/opinion/8852666/consolidated-roller-mill-co-v-coombs/.
2. Treat the assertion as a fraud/abuse signal, not a merits dispute. A demand letter on a long-expired, judicially-invalidated 1883 patent warrants a documented refusal and, depending on jurisdiction and conduct, consideration of state-law or fee-shifting responses. Preserve the letter.
3. If your interest is defensive prior art rather than defense of an assertion, US 289,518 remains a usable printed publication (1883-12-04) for § 102(a)(1)/§ 102(b) art against later roller-mill feed-mechanism claims, and it is cited in the specification of later patents such as US 2,925,203 and US 3,830,408. Cite it as a publication, not as a proceeding.
4. No docket monitoring is required. There is nothing to watch — no institution deadline, no oral hearing, no one-year FWD clock, and no appeal. Any future AIA-trial activity on this patent number can be ruled out categorically; if a "PTAB proceeding on US 289,518" is ever represented to you by a third party, that representation is false.

I'll start by checking the authoritative sources for any recorded assignment activity on this patent.

The assignment database's coverage is 1970/1980–present, which is a critical threshold for an 1883 patent. Let me check whether any modern record exists and gather historical ownership context.

Let me check the historical owner referenced in the litigation and any modern-record traces.

Inventors

Findings and caveats:

• Sole inventor. The patent lists no joint inventors, and the specification signature block names only "DANIEL E. DOWLING" (witnessed by Patrick Farrell and Robert F. Crawford — the only agents/representatives named anywhere on the document).
• Name discrepancy flagged, not corrected: the OCR'd heading of the granted specification reads "DANIEL n. BOWLING, OF NEW YORK, N. Y.," while the body reads "DANIEL E. DOWLING, of Brooklyn, in the county of Kings and State of New York." The body text and the claims signature ("DANIEL E. DOWLING") control; the heading is an OCR/typographic corruption. This matters for any assignment-name search: searching "Bowling" will return nothing.
• Filing September 4, 1882 (No model); issued December 4, 1883, as US 289,518, "Feed Mechanism for Roller-Mills."
• The "all inventors departing within 12 months of filing" pattern is not assessable — there is no employment relationship, no assignor entity, and no personnel record to measure against. There is also no corporate co-inventor to indicate the invention was made in the course of employment for a mill builder. Nothing in the four claims (two grinding rolls + rotary feed roll + hopper with one-sided throat + adjustable gate + lengthwise-reciprocating toothed agitator bar) ties the inventor to a named manufacturer.

Original assignee

None. The patent issued to Dowling individually, with no assignee named on its face.

• There is no "Assignee:" field on the granted patent, and the Google Patents record for US289518 shows no assignee, no current-assignee entry, and no legal events other than a placeholder "Expired – Lifetime" status with an anticipated expiration of 1900-12-04 (17 years from the 1883 grant under the then-applicable term). That Google status is a database placeholder keyed to the statutory term; it is not evidence of a recorded ownership transfer.
• Because there is no issuing assignee, the three questions in this section (did they ship a product embodying the claims / primary line of business / current status) cannot be answered for an "original assignee." Dowling's own commercial activity is not established by any source I can verify — I decline to characterize him as an independent inventor or as a mill-company employee, because the record does not say.
• Historical possessor of the patent, evidenced outside the assignment record: in Consolidated Roller-Mill Co. v. Coombs, 39 F. 25 (C.C.N.D.N.Y. 1889) (https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.html), the Consolidated Roller-Mill Company — a roller-mill manufacturer — sued for infringement of claims 1, 3 and 4 of the Dowling patent, alongside the Gray patent (No. 228,525) and the Marmon patent. The court held the Dowling combination "but an aggregation of old elements adapted to a new machine," found no invention, and dismissed the bill as to the Dowling and Marmon patents; the plaintiff took relief only on Gray. The same company litigated the Gray/Marmon roller-mill family to the Supreme Court (Consolidated Rolling-Mill Co. v. Barnard & Leas Mfg. Co., 156 U.S. 261 (1895); Consolidated Roller-Mill Co. v. Walker, 138 U.S. 124 (1891)).
• Standing to sue implies Consolidated Roller-Mill acquired Dowling's rights (by assignment or exclusive license), but no recorded instrument confirming that transfer is available in any searchable database — it would predate the assignment-recording coverage by roughly a century. Treat "Dowling → Consolidated Roller-Mill Co." as a probable, unrecorded pre-1900 transfer inferred only from the 1889 pleading, not as a finding.
• Status of Consolidated Roller-Mill Co. today: not determinable from sources checked; the Gray patent term expired in the 1890s and the entity does not appear in the modern assignment/asserter indices.

Assignment timeline

No assignment records exist for US 289,518 in the USPTO Patent Assignment Search.

Plainly stated: searching patent number 289518 on the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) returns nothing, because the underlying dataset does not reach this patent. The searchable "Assignments on the Web" data covers only August 1980 to present, and the bulk USPTO Patent Assignment Dataset covers 1970 to present (https://www.uspto.gov/ip-policy/economic-research/patent-assignment-dataset). A patent that issued in December 1883 and expired in 1900 falls outside both windows. The same limitation is reflected in the record for this patent on Google Patents (https://patents.google.com/patent/US289518/en), which lists no assignee and no legal events — the only "family" entry ("US289518D") is an artifact of Google's OCR of the manuscript publication listing, not a separate application or a recorded transfer.

Correspondingly, there are no reels/frames, no conveyance types, no assignors, no assignees, and no correspondents of record to report. I cannot cite a reel/frame for this patent, and I will not construct one. The only named representatives on the document at all are the two specification witnesses (Patrick Farrell; Robert F. Crawford) — not assignment-record correspondents, and with no recurrence data attached to them in this chain. Modern documents citing this patent (US2925203A, Armstrong Cork Co., "Volumetric feeder," 1960; US3830408A, Crosse Cooler Co., "Ice cube storage hopper and dispenser," 1974) are examiner/third-party citations, not transfers of interest, and neither assignee ever held title to 289,518.

Per the operating rule for this analysis, the record ends here: with no recorded assignment links, the timeline diagram, NPE/troll-pattern signal matrix and verdict sections are not reachable for this patent, and any of them I produced would be invention rather than analysis. For completeness of classification under the protocol: on a chain of title consisting of the original grant alone, with no post-issuance recording, the result is Insufficient data — the 1883 grant to Dowling plus an unverifiable pre-1900 transfer of rights to a roller-mill manufacturer that asserted (and lost) the patent in 1889. To go further you would need paper-era sources outside the digital assignment system: the National Archives patent assignment deed books (Record Group 241, pre-1936 assignments) and the Consolidated Roller-Mill Co. corporate records — worth ordering only if the pre-1900 chain itself is the research objective, since no NPE, shell-entity, privateering or defensive-aggregation signal can attach to a patent in the public domain for 125 years.

I'll run targeted searches for this exact number and for each citation/document linked on its record.

Key finding surfacing: this patent was litigated. Let me dig into the case and the sibling references.

Prior-Art Analysis — U.S. Patent No. 289,518

Step 1 — What the record for 289518 actually shows

Threshold finding, stated plainly: U.S. Patent No. 289,518 has no examiner-cited patent references on its face, and no "References Cited" list appears on the authoritative record.

The fetched record (https://patents.google.com/patent/[US289518](/patent/US289518)/en) contains three distinct citation-type blocks, and only one of them is a citation at all:

I could not retrieve any USPTO PatentCenter examination record, file-wrapper citation listing, or assignment instrument supplying citations for this number. For an 1883 grant, the printed patent face is the citation record, and it is blank. I am reporting that as a negative result rather than importing references from elsewhere and labeling them "citations for 289518."

Two cross-reference flags against the previously generated sections:

• Date contradiction (minor): your task header says "Current Date: April 26, 2026," while the prior section's fetched-page timestamp and my working date are 2026-09-30. It does not affect the analysis (this patent is 143 years expired either way), but per your instruction I am flagging it rather than silently harmonizing.
• Supplement, not contradiction: the prior section correctly noted "no assignee stated." The litigation record below independently confirms the patent was held by the Consolidated Roller-Mill Co. as an asset by 1889 — i.e., an assignment occurred post-issue even though none is printed on the patent. That is new information, not a correction.

Step 2 — Forward citations ("Cited By") — analyzed, then excluded

These are the only actual citations on the record. Both are irrelevant as § 102 art because both postdate 289,518 by 65–90 years and because a patent cannot anticipate earlier art.

Step 3 — The § 102 framework for a patent filed 1882-09-04

A necessary correction before the anticipation analysis: 35 U.S.C. § 102 did not exist when this patent was granted. It was enacted in the Act of July 19, 1952. The governing provision on 1883-12-04 was R.S. § 4886 (Patent Act of 1870), which barred a patent where the invention was "known or used by others in this country, or patented or described in any printed publication in this or any foreign country, before his invention or discovery thereof."

I apply § 102 below because you asked for that rubric, but the honest mapping is:

• § 102(a)/(b) "patented or described in a printed publication" ↔ R.S. § 4886 "patented or described in any printed publication."
• Critical date: Dowling's filing date, 1882-09-04, is the presumptive constructive date of invention. Anything published before 1882-09-04 is squarely available. Anything between 1882-09-04 and 1883-12-04 is not available for anticipation absent proof of a date of invention earlier than the reference (the Alexander Milburn doctrine of later-filed, earlier-published art did not exist in 1883 and is not being applied).

Step 4 — The reference categories that DO bear on validity

4(a) Conceded prior art in the specification (unnamed — no citation identity exists)

The specification contains the only prior-art statements the inventor himself put on the record. These are A-type admissions, and because they are unnamed, they cannot be given a citation or a date:

Anticipation effect: These admissions are why claims 1–4 survive as a group at all. Each named combination lacks the one element the claims require — an agitator reciprocating in the direction of the feed-roll axis. The specification expressly states "to such combinations I lay no claim." A reference showing only a rotary or transverse-vibrating agitator cannot anticipate any of claims 1–4 as written, because each independent claim recites lengthwise/axis-direction reciprocation.

4(b) The judicial record — the single most probative prior-art finding

Consolidated Roller-Mill Co. v. Coombs, reported at 39 F. 25, U.S. Circuit Court, District of Michigan (bill involving Gray, Dowling, and Marmon patents).

• Sources: https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.pdf ; https://ia800304.us.archive.org/26/items/gov.uscourts.f1.039/039.f1.pdf ; https://www.courtlistener.com/opinion/[8852666](/patent/8852666)/consolidated-roller-mill-co-v-coombs/
• The court's statement of the defenses: "The chief defenses to the Dowling and Marmon patents are want of invention, in view of the prior state of the art."
• The disposition: "the defendant is entitled also to have inserted therein a clause dismissing the bill as to the Dowling and Marmon patents" — and the companion decision confirms the tally: "The complainants abandoned one of the patents at the hearing. The court held two of them invalid, and sustained the second, third, fourth, and fifth claims of the other, the Gray patent" (Consolidated Roller-Mill Co. v. Richmond City Mill-Works, 40 F. 474, 1889).
• The court also characterized the Dowling subject matter as: "The prominent feature of this combination is the centrally-located agitator, introduced for stirring up the material, and thereby [delivering it uniformly]."

Bottom line: U.S. 289,518 (Dowling) is one of the two patents judicially held invalid in that litigation. The surviving claims were Gray's. I have not verified from the retrievable snippets the precise ground (want of invention vs. § 4886 anticipation) as to Dowling specifically — the opinion text describing the Dowling analysis is only partially visible in the retrievable pages, and I will not fabricate the holding's exact wording. This is the highest-priority item for anyone who needs a definitive answer: obtain the full text of 39 F. 25, the Dowling section.

4(c) Art identified in the litigation and its surrounding record (candidate § 102/§ 4886 references)

These are the references the defendant's case was built on and that describe the state of the roller-mill art as of 1882:

4(d) The "Similar Documents" block — analogous art, NOT citations

I want to be explicit that these were not cited against 289,518 by anyone. They are Google's similarity cluster. I include them because your task asked for "the most relevant prior art," and this is the only pre-1882 roller-mill/feed-mechanism set on the record. Dates below are publication dates as printed on the fetched record; I have not verified filing dates, which is essential to any § 4886 analysis.

Pre-1882-09-04 — available for anticipation:

Post-1882-09-04 — NOT available as § 102 art against Dowling (no § 102(e) doctrine in 1883):

4(e) Analogous art found independently (not on the 289,518 record at all)

These surfaced in my search as the actual technical antecedents of the conceded disclosures. They are offered as § 102/§ 4886 candidate art, clearly labeled as not citations of 289,518:

Step 5 — Direct answers to your questions

"Search the USPTO database for the specific patent number 289518."
US 289,518 A is confirmed: Daniel E. Dowling, Brooklyn, Kings County, New York; Feed Mechanism for Roller-Mills; filed 1882-09-04 (No model); granted 1883-12-04; expired 1900-12-04. It is the only record at that number; I have not substituted any similar number.

"Look at each patent citation for 289518."
There are zero backward patent citations. The only citations on the record are the two forward citations — US 2,925,203 (1960) and US 3,830,408 (1974) — and neither can be § 102 art. The "Similar Documents" list is a database similarity cluster, not a citation list, and I have not mislabeled it as one.

"Identify the most relevant prior art."
Ranked, in order of legal significance to claims 1–4:

1. The unnamed conceded art in the specification itself (rotary agitators above a feed-roll; agitators vibrating transverse to the roll axis; spiral agitators/screws). This is the only prior art the applicant himself put on the record, and it is the art that defines the claims' scope. It anticipates nothing, because no admitted reference shows axis-direction reciprocation.
2. The Coombs / 39 F. 25 trial record — the defendant's prior-art case, on which the Dowling patent lost. This is where the anticipation and want-of-invention evidence against 289,518 actually lives. Obtaining the full Downing section of that opinion is the single highest-value next step.
3. US 261,337 A (1882-07-18) and US 260,669 A (1882-07-04) — the only pre-filing "similar documents" directly on-point by title. These are the references most likely to have been in the defendant's proof. Content unverified.
4. US 288,808 A (1883-11-20) — same title, issued two weeks earlier. Not § 102 art on its face, but the one reference whose filing date could change that conclusion. Unresolved.
5. US 216,617 A (1879-06-17) and US 248,802 A (1881-10-25) — element-level feed-roll/roller-mill art; cannot anticipate a combination claim alone.
6. US 111,593 (1871) and US 252,211 (1882-01-10) — the screw-feed and stone-mill uniform-feed art that the specification already disclaimed.

"Which claim(s) it potentially anticipates under § 102."
Stated with the confidence the evidence supports: I have not found a reference that anticipates any of claims 1–4 of US 289,518. Every reference I can actually examine lacks at least one element of each independent claim — and in every case the missing element is the same one: an agitator reciprocating in the direction of the feed-roll axis, with teeth terminating at/near the feed-roll surface or feed-throat. That element is the stated essence of the invention and the recited core of all four claims. The strongest candidates for anticipation (US 261,337; US 260,669; the Coombs record) are precisely the ones I could not read, and I am flagging them as open rather than resolving them by inference.

Uncertainty flags (required)

• Backward citation block: absent. Do not attribute any patent citation to the face of 289,518. To my knowledge, none exists.
• Claims 3 and 4 remain OCR-interleaved in the authoritative text (as flagged in the prior section); the element-level novelty analysis above rests on claim 1's undisputed recitation and on the specification's statement of the essential feature, both of which are clean.
• Filing dates of the "Similar Documents" references are not in the retrieved record. Publication dates alone are insufficient for a § 4886/§ 102 determination where a reference published in the 1882-09-04 → 1883-12-04 window.
• Coombs holding as to Dowling: the dismissal of the bill as to "the Dowling and Marmon patents" is documented; the ground (anticipation vs. want of invention) is not fully visible in the retrievable text. Do not characterize the holding more precisely than the sources support.
• Coombs reporter/court/date: the opinion appears at 39 F. 25; the exact circuit, division, and decision year were not fully confirmed in the retrieved snippets. Verify before citing.
• Marmon patent number: I could not verify it. The record only says "the Marmon and Warrington patent," twelfth claim.
• The unrelated '518 numbers (Kaifi '518, etc.) remain excluded per your instruction, as noted in the prior section.

Sources: https://patents.google.com/patent/US289518/en (authoritative record) · https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.pdf · https://ia800304.us.archive.org/26/items/gov.uscourts.f1.039/039.f1.pdf · https://www.courtlistener.com/opinion/8852666/consolidated-roller-mill-co-v-coombs/ · https://www.cetient.com/case/consolidated-roller-mill-co-v-richmond-city-mill-works-[8853526](/patent/8853526) · https://tile.loc.gov/storage-services/service/ll/usrep/usrep138/usrep138124/usrep138124.pdf · https://patentimages.storage.googleapis.com/.../[USRE10979](/patent/USRE10979).pdf · http://aicmc.fr/includes/brevets/[US266182](/patent/US266182).pdf · https://patentimages.storage.googleapis.com/.../[US281814](/patent/US281814).pdf · https://patentimages.storage.googleapis.com/de/e2/7a/b17efbfc3be6af/[US111593](/patent/US111593).pdf · https://patentimages.storage.googleapis.com/c1/36/3c/b0ebcccbdaa687/[US252211](/patent/US252211).pdf · https://patentimages.storage.googleapis.com/5f/ed/f9/335f637ecffbfb/[US335257](/patent/US335257).pdf

I'll ground the analysis by checking what the record's prior-art references actually disclose, then build the §103 case.

The search surfaced something directly on point — actual 19th-century litigation over this patent. Let me pin it down before writing.

Obviousness Analysis — U.S. Patent 289,518 (Dowling, "Feed Mechanism for Roller-Mills") under 35 U.S.C. § 103

Two contradictions with the previously generated sections must be flagged up front (see §1 below), and the most important development is that the search surfaced the 1889 decision that actually adjudicated this patent's claims — which supplies a ready-made, contemporaneous "want of invention" holding on the same combination the § 103 inquiry targets.

1. Contradiction flags against the earlier-generated sections

1.1 Claim 4's text (material)

The earlier "Independent claims" section reconstructed claim 4 as reciting "teeth terminating at or near the feed-throat," and expressly warned of OCR interleaving. That reconstruction is wrong. The 1889 court quoted claim 4 verbatim:

"(4) In a grinding-mill, the combination of two grinding-rolls, the feed-roll above the same, a hopper above the feed-roll, and a toothed agitator centrally located within the hopper and extending lengthwise above the feed-roll, and mechanism for reciprocating said agitator in a lengthwise direction." — Consolidated Roller-Mill Co. v. Coombs, 39 F. 25 (full text; mirror)

The court found claim 4 "contains the clearest statement of the combination." "At or near the feed-throat" is claim 3 language, not claim 4. Any element-by-element chart built on the earlier reconstruction must be corrected.

1.2 Claim 4 is not the only independent claim, but it is the operative one

The earlier section said all four claims read as independent. Coombs only asserted claims 1, 3, and 4 and treated claim 4 as dispositive. Claim 2 was not asserted and was not construed.

1.3 Minor

The task header says "Current Date: April 26, 2026," while the system context and the page fetch timestamp both read 2026-09-30. Immaterial to the analysis; noting it because I was instructed to flag contradictions.

2. Threshold: § 103 is an anachronism here — but the 1889 equivalent was actually applied

35 U.S.C. § 103 did not exist when this patent was granted. US 289,518 issued 1883-12-04 under the Patent Act of 1870 (R.S. §§ 4886 et seq.) and expired 1900-12-04 (17 years from grant, R.S. § 4884 — matching the "Anticipated expiration" field on the Google Patents page). The nonobviousness requirement of that era was the judicially created "invention" standard of Hotchkiss v. Greenwood, 52 U.S. (11 How.) 248 (1851) — "more ingenuity and skill … than were possessed by an ordinary mechanic acquainted with the business" — policed through the "aggregation vs. combination" and "new result" doctrines.

So the honest framing is:

• A modern § 103 analysis of this patent is counterfactual. I will run it as requested, using the Graham/KSR framework, but with a POSITA whose knowledge is fixed as of 1882–83.
• The same question was actually litigated. In Consolidated Roller-Mill Co. v. Coombs, 39 F. 25 (C.C.S.D.N.Y. 1889), the defendant raised "want of invention, in view of the prior state of the art" against the Dowling patent, and the court dismissed the bill as to the Dowling patent: "[T]he defendant is entitled also to have inserted therein a clause dismissing the bill as to the Dowling and Marmon patents" (the plaintiff took its decree on the separate Gray patent). (vlex case summary)
• One caveat I cannot resolve from this record: whether Coombs was appealed or affirmed. The report at 39 F. 25 is a circuit-court opinion; a companion ruling at 39 F. 803 concerns staying an injunction. Whether an appellate affirmance exists is not established here.

Consequence: the § 103 conclusion below is not speculative. It is the conclusion a reviewing court in the same era reached, on a record that included specific prior patents, and the reasoning is structurally the KSR rationale (familiar elements + predictable result) that a modern examiner would use.

3. The prior art of record

3.1 Group A — references the page's "Prior Art" section supplies (titles/dates only)

3.2 Group B — the two "Cited By" references: ineligible

US 2,925,203 A (Armstrong Cork, filed 1957-12-18) and US 3,830,408 A (Crosse Cooler, filed 1972-11-10) post-date US 289,518 by 74 and 91 years. They are not prior art against it under any subsection of § 102, and per the earlier section they are near-certainly examiner/third-party citations arising in unrelated later cases. They contribute nothing to the § 103 case.

3.3 Group C — the applicant's own admissions in the specification (binding as prior art)

These are the strongest § 103 material on the face of the patent, because a patentee's specification admissions about the prior art are treated as prior art against him:

1. "a feed-roll has been combined with rotary agitators above the same";
2. "agitators arranged to vibrate in planes transverse to the axis of the said roll";
3. "spiral agitators or screws have been arranged above the surface of a feed-roll in a grinding-mill";
4. hoppers "combined with agitating and feeding mechanism of various kinds therein" in machines for grading and separating grain and in machines for sowing wheat.

Admissions 1–3 expressly concede that agitator element (b) and host structure (a)/(c) were known in roller-mill feeding; the only remaining variable is the direction of agitation relative to the roll axis. Admission 4 concedes the hopper-agitator combination in other arts.

3.4 Group D — the references actually used to invalidate the claims in 1889 (the decisive set)

Coombs identifies specific art that is on all fours with the claims:

OCR caution, per your no-auto-correction rule: the retrieved text prints the surname variously as "Caine"/"Cains," "II. E. Keeler" (likely "H. E. Keeler"), "farming-mill" (likely "fanning-mill"), and "No. 137,0.51." I am reporting the identifiers as printed and flagging that all of Caine 78,423 / 137,051, West 100,573, Keeler 254,140, and the unknown Mahaffy number should be pulled from the printed patents or the Federal Reporter volume 39 PDF before being relied on in a written opinion. Keeler No. 254,140 is the one whose eligibility needs a date check: the numbering sequence (US 251,826 = 1882-01-03; US 261,337 = 1882-07-18) places it roughly in spring 1882, i.e. before Dowling's 1882-09-04 filing — but that must be verified rather than assumed.

Net effect: Caine supplies elements (b), (d), and (e) of claim 1 in a single reference, in a hopper-feeder context, with the same cam drive. West and Keeler supply the "centrally located" placement limitation of claims 3–4.

4. Claim element charts

4.1 Claim 1

Result: every element of claim 1 is disclosed by Caine alone in the roller-feeder context, with the hopper/gate geometry being conventional. Claim 1 is obvious (and, if Caine's disclosure is as the court characterized it, arguably anticipated under § 102).

4.2 Claim 2 (adds the adjustable gate and the "feed-bar … with depending teeth")

Result: obvious. Limiting the throat to one side is the only element not squarely addressed by the retrieved art, and I address its residual weight in §6.

4.3 Claim 3

Adds "toothed agitator centrally located within the hopper … extending lengthwise above the feed-roll" + the gate. Placement is met by West No. 100,573 (adjuster centrally located) and Keeler No. 254,140 (similar device similarly located). Obvious — and note that "extending lengthwise above the feed-roll" appears verbatim in Caine's arrangement (the agitator rod runs lengthwise over the revolving stirrer).

4.4 Claim 4 — the claim actually adjudicated

"the combination of two grinding-rolls, the feed-roll above the same, a hopper above the feed-roll, and a toothed agitator centrally located within the hopper and extending lengthwise above the feed-roll, and mechanism for reciprocating said agitator in a lengthwise direction."

The Coombs court's holding is the answer:

"Dowling's combination of the two grinding-rolls, the feed-roll above the same, a hopper above the feed-roll, (used in all roller-mills,) and the toothed agitator of the Caine, West, Keeler, and Mahaffy patents, centrally located, as in the West and Keeler patents, and the mechanism for reciprocating such agitator in a lengthwise direction, is but an aggregation of old elements adapted to a new machine, but producing practically the same results. We do not think that any invention is involved in putting these devices together, and placing them in the hopper of a flouring-mill."

Mapped onto § 103, that is the "combination of familiar elements according to known methods yielding predictable results" rationale (KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007)).

5. Why a POSITA would have been motivated to combine — articulated rationales

1. Same field of endeavor / reasonably pertinent to the problem. Caine, West, and Keeler are hopper-feeders for particulate material; the problem Dowling states (material "bank[ing] up or bridg[ing] over in the hopper when soft," delivered unevenly "from one end of the rolls to the other") is precisely the problem those references solve. Under In re Bigio / In re Clay, a reference need only be reasonably pertinent to the problem, not to the patentee's own field.
2. Same function, same mechanism. The court found the modes of operation "practically the same" as lump-breaking agitators used for plaster, ashes, lime and manure — i.e., the toothed comb over a feed roller was a known, transferable expedient.
3. The 1889 court itself articulated the motivation. Caine's agitator was not centrally located — it "lies flat against one of its sides" — and the only step needed was to move it to the center, which West and Keeler already did. A missing placement for a known agitator, supplied by references that place the same agitator in the same place, is the paradigm § 103 combination.
4. The host machine was admitted to be old. The roller-mill + hopper + feed-roll sub-combination is in "all roller-mills" (Dowling's own admission, admission (1); the court's finding).
5. Predictable result / design choice. Positioning an agitator at the center of a hopper mouth to prevent bridging is a matter of mechanical design choice with an expected outcome; no new function is produced. KSR, 550 U.S. at 421; A&P Tea Co. v. Supermarket Equipment Corp., 340 U.S. 147, 152 (1950) (pre-1952 analogue: "the whole must exceed the sum of its parts").
6. Finite, identified set of solutions ("obvious to try"). The conceded agitator motions were rotary, transverse-vibratory, and spiral-screw — three of the available options. Axial reciprocation was the remaining orientation, and the admitted spiral screw already teaches axial material transport above a feed-roll, so the direction of movement along the roll axis was known to be the variable that controls end-to-end distribution.
7. Result-effective variable for the gate. Adjusting a hopper throat by screw-driven gate to vary feed rate is an adjustable parameter whose effect on feed rate is recognized — obvious to optimize (In re Boesch; In re Antonie).

6. The patentee's best rebuttals, and how they fare

7. What I cannot establish on this record (verification checklist)

1. Actual disclosures of Caine 78,423 / 137,051, West 100,573, Keeler 254,140, and Mahaffy — I rely on the Coombs court's characterization, not on the printed patents.
2. Keeler No. 254,140's issue date — must precede 1882-09-04 (or Dowling's invention date) to be § 102(a) art. Also the Mahaffy patent number, which the retrieved text omits.
3. Caine No. 137,051's date — need to confirm it predates the critical date; No. 78,423 (1868-era numbering) plainly does.
4. Appellate history of Coombs — whether the Dowling invalidity holding was affirmed.
5. Contents of the analogous-art admissions (grain-grading/separating and wheat-sowing machines) — the specification concedes them but names no patents.
6. Google Patents' "Prior art date: 1883-12-04" is simply the issue date of US 289,518; it is not an evidentiary prior-art date for anything.
7. Whether any of the Group A "Similar Documents" (notably US 216,617 and US 261,337) disclose an axial-reciprocating agitator — if either does, claim 1 becomes an anticipation case (§ 102), not merely § 103.

8. Bottom line

Applying § 103 (as a counterfactual modern analysis) to US 289,518:

• Claims 1, 3, and 4 are obvious over Caine No. 78,423 and/or No. 137,051 (cam-driven, lengthwise, toothed reciprocating agitator with saw-like teeth resting on or near a revolving feed-roller in a hopper) in view of West No. 100,573 and/or Keeler No. 254,140 (centrally located agitator), further in view of the roller-mill/feed-roll/hopper combination admitted to be in all roller-mills in Dowling's own specification.
• Claim 2 is obvious for the same reasons plus Burkhart US 251,826 (screw-adjusted gate regulating feed).
• The result is not merely my reconstruction: in Consolidated Roller-Mill Co. v. Coombs, 39 F. 25 (C.C.S.D.N.Y. 1889), the court construed claim 4, applied the era's "want of invention" standard to the same combination, and held it "an aggregation of old elements adapted to a new machine, but producing practically the same results," dismissing the bill as to the Dowling patent.
• The two "Cited By" references on the Google Patents page (US 2,925,203; US 3,830,408) are legally incapable of being prior art against an 1883 patent and should be excluded from any chart.
• Residual uncertainty rests on the "at one side only" throat limitation of claim 1 (untouched by Coombs) and on whether Caine's cam-driven agitator is as close as the court's characterization makes it appear — a point that should be verified against the printed references before the conclusion is put in writing.

Confidence: high (≈0.85) that claims 1–4 would be held invalid for obviousness/want of invention; slightly lower on claim 1 alone because of the unadjudicated one-sided-throat limitation.

Sources: https://patents.google.com/patent/[US289518](/patent/US289518)/en (authoritative full text); https://law.resource.org/pub/us/case/reporter/F/0039/0039.f.0025.html and https://app.midpage.ai/document/consolidated-roller-mill-co-v-coombs-[8838072](/patent/8838072) (verbatim quotation of claim 4 and the want-of-invention holding); https://case-law.vlex.com/vid/consolidated-roller-mill-co-895475035 (defenses and outcome); https://patents.google.com/patent/[US251826A](/patent/US251826A)/en (screw-adjusted feed slide); https://patents.google.com/patent/[US949400A](/patent/US949400A)/en (post-dating lineage).