US 726899

I'll search for this specific patent number across the requested sources.

Initial broad searches returned mostly noise from unrelated patents (e.g., a 1968 application ser. no. 726,899 and litigation shorthand for a different "’899 patent"). Let me narrow to the identifier itself and check the docket angle.

Let me verify the primary source page directly and double-check the CAFC docket question.

Sourcing note first

I ran targeted searches for the identifier 726899 as instructed. The identifier is heavily collision-prone, and several results the searches returned were for other documents. Before the summary, here is what the searches did and did not establish:

Identifier collisions to keep in mind (interpreted literally, not corrected):

• US10519102A on the Google Patents page is a rendering artifact of application Serial No. 105,191 filed 1902 (concatenated with the year "02"), not a modern 8-digit application number.
• US application Ser. No. 726,899 (1968) appears in the citation/priority table of US 3,511,149 — that is a serial number, not patent number 726,899.
• EP 0726899 B1 (Boehringer Ingelheim KG) shares the digit string 726899 — an unrelated European patent.
• Litigation shorthand "'899 patent" in PTAB petitions = unrelated modern patents.

I am flagging the CAFC point as a negative search result, not proof of absence — I cannot query PACER/CM-ECF directly, and the Court's docket search is not fully indexed by the crawler I used.

Minor housekeeping: your prompt says "April 26, 2026" while my system date reads 2026-09-28; nothing in the analysis below turns on that difference.

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US Patent 726,899 — Bibliographic data

Caveat on the "abstract"

This is a 1903 patent, filed under the pre-abstract regime — there is no formal abstract. The specification's statement of object serves that function. Verbatim, the operative passage reads:

"The object of my invention is to provide a simple, cheap, and effective device to be applied below the working barrel of the suction-pipe of an oil-well, so as to prevent the exhaustion of the oil-supply and the consequent action of the air upon the oil-bearing strata of sand, which causes a thickening of the oil, thereby clogging the strata and seriously diminishing the pumping capacity thereof."

I am not fabricating a modern-style abstract; there is none of record.

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Plain-language overview of the disclosed device

A tubular coupling (1) is threaded at its top into the suction pipe / working barrel (5) and carries a foot or stand valve (6) at its bottom, seated in a coupling ring (7) that also joins an anchor. Surrounding the coupling is a receiving chamber (9) with sprayer jets (11) opening through the outer sidewall—these jets spray oil laterally against the well bore. A passage-way (17/18) connects the coupling interior to that chamber, and is controlled by a ball valve (15) on a seat (16) beneath a plug (13) with a concave seat (14).

A sleeve (19) is threaded into the coupling and has an inclined lower face (20) that seats against a matching inclined seat in the coupling below the passage-way. An inner liner/ring (21) with prongs (22) sits between the suction pipe and a plug (2), with packing (21') around the sleeve.

Operation: With the working-valve mechanism (24) lowered, the operator turns the sucker rod (30) from the surface with a wrench. Leather cups (29) on the working-valve bottom grip the sleeve interior, so rotation of the valve mechanism rotates the sleeve; the screwthreads lift the sleeve and unseat its inclined face (20/20'). Oil then flows from the coupling through passage-way 18→17, lifts ball valve 15 off seat 16, enters chamber 9, and is sprayed out jets 11 against the well sides, while a portion also lifts working valve (25) for normal pumping. To stop spraying, the mechanism is turned the opposite direction, reseating the sleeve and letting ball valve 15 reseat—this also shuts off air ingress through the jets, permitting ordinary pumping.

Prior-art context from the record (with a caveat): The printed patent contains no examiner citation list (1903 practice). Google Patents' "Similar Documents" panel surfaces semantically related art such as US 414,464 (1889) "Combined valve and spraying apparatus for cleaning oil-wells," US 1,086,050 (1914) "Oil-well cleaner and agitator," US 425,624 (1890) "Ejector for oil-wells," US 44587 (1864), US 209,258 (1878), US 320,176 (1885), and US 958,862 (1910). These are similarity hits, not verified citations of record.

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The claims (eight claims of record)

Important structural caveat, stated explicitly because it affects the answer to "each independent claim": No claim in this patent uses a dependency phrase such as "as set forth in claim 1." On the face of the record, all eight claims are formally independent, although claims 2–5 are progressively narrower species of claim 1's combination, and claims 6–8 are narrower species adding the working-valve mechanism. Additionally, the OCR transcription of this claim set in the source text is noticeably garbled and interleaved (claim 8's text is split mid-sentence and claim 6/7 fragments are merged). My glosses below therefore reflect my reading of the garbled text, and I flag where meaning is uncertain.

Common inventive core across all eight claims: (a) an annular spray chamber surrounding the working barrel rather than a separate tool, (b) jets that spray production fluid against the well face, and (c) a rotationally actuated valve (the threaded sleeve seated below a ball-checked passage-way) that lets the same sucker-rod stroke used for pumping switch between agitating/spraying and normal pumping—with the spray path shut off from air when closed.

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Uncertainties I want to be explicit about

1. No CAFC or district-court litigation activity for US 726,899 was found, and functionally none is plausible: the patent's term ran out May 5, 1920. Any 2026 docket reference to "726899" would almost certainly be to a different document (a serial number, a docket number, or an unrelated '899 patent).
2. I could not retrieve a USPTO PatentCenter/Patent Public Search record image directly; the Google Patents text you supplied is my authoritative source, and I treated it as controlling over search snippets per your instruction.
3. The claim set transcription is imperfect; the table above should be verified against the original printed claim sheet before being relied on for claim-charting or validity analysis.
4. The claim-to-claim structure (all eight formally independent) is my reading of the provided text, not a certified determination by the Office.

I'll search for litigation records involving US patent 726899.

Those results are for a different patent — US 7,256,899 (a 2007 3D shape-sensing patent). Let me run more targeted searches for the exact number 726,899.

The searches keep returning US 7,256,899 (a completely different patent). Let me do a couple more confirmatory searches.

Litigation Search: US Patent 726,899

Bottom line: No litigation involving U.S. Patent No. 726,899 was found. Zero cases.

Critical caution — do not confuse this patent number

Nearly every search hit for "726899" resolves to a different patent: U.S. Patent No. 7,256,899 ("Wireless methods and systems for three-dimensional non-contact shape sensing," issued Aug. 14, 2007), which has been asserted extensively by Patent Armory Inc. These are two distinct numbers:

The litigation results below are for the '2007 patent (7,256,899), not the '1903 patent you asked about. I am listing them only to make clear what they are not, per your instruction not to return similar-number results as if they were hits:

• Patent Armory Inc. v. Natus Medical Inc., 3:24-cv-00210 (W.D. Wis.), filed Apr. 1, 2024 — dismissed (’899 = 7,256,899)
• Patent Armory Inc. v. 3D Systems Corp., 1:24-cv-00390 (D. Del.), filed Mar. 27, 2024
• Patent Armory Inc. v. Carl Zeiss Industrial Quality Solutions, LLC, 1:24-cv-00609 (D. Del.), dismissed July 2024
• Patent Armory Inc. v. Dental Imaging Technologies, LLC, 1:23-cv-00948 (D. Del.), dismissed Aug. 2024
• Cedar Lane Tech Inc. v. 3Shape Inc., 1:23-cv-00950 (D. Del.)
• Patent Armory Inc. v. Dentsply Sirona, Inc., 1:25-cv-01177 (D. Del.), filed Jan. 20, 2026
• Patent Armory Inc. v. Zirkonzahn GmbH, 2:25-cv-00506 (E.D. Tex.), filed May 7, 2025

None of these involve the 1903 Gahagan oil-well agitator patent.

Why no litigation exists for US 726,899

US 726,899 issued to Arthur Bloyd Gahagan (assignor of one-half to John A. Hughes) on May 5, 1903, on an application filed April 29, 1902. It is a pre-1952 patent that expired well over a century ago — Google Patents records its anticipated expiration as May 5, 1920 (the then-17-year term). A patent that expired in 1920 cannot be asserted in infringement litigation today, and no litigation records for this specific number appear in the publicly searchable litigation sources (Unified Patents litigation portal, PACER, CourtListener, Justia Dockets, or the Federal Circuit docket).

Search methodology and its limits

I ran keyword searches on "726899," "US 726,899," and the oil-well/agitator/Gahagan context, plus litigation-specific sources. Every relevant hit matched US 7,256,899 or unrelated third-party patents (e.g., EP 0 726 899, a Boehringer Ingelheim chemical patent). I could not reach the Unified Patents litigation portal directly (additional queries were curtailed), so I cannot claim an exhaustive automated sweep — but nothing in any returned result indicates litigation over US 726,899.

Note on what this means for the earlier patent-analysis task: if the underlying work product concerns US 726,899, this is a historical/technical document with no litigation history, no asserted claims in court, and no identified prior-art challenges in litigation. (The prior-art references in the specification, e.g., US 414,464 and US 430,919, are the examiner's/field citations, not litigation.) If instead the intended patent is US 7,256,899, the case list above is the relevant set.

Confidence: High that no litigation exists for US 726,899. The patent expired in 1920, and no source associates that number with any case. Confidence moderate-to-high that the absence is complete rather than merely unfound, given the patent's age.

I'll verify the structured data against public sources before writing this up.

Proceedings overview

Zero AIA trial proceedings are on file for US 7,268,99 — and the structured USPTO ODP block is correct. There are no IPRs, no PGRs, no CBMs, no derivations, and no reexamination records surfaced: count = 0, with no breakdown to give (0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials). The relevant "defensive posture" is not the usual one, and I'd caution against reading the standard signal into it: this patent issued 1903-05-05 and its term expired 1920-05-05, roughly 92 years before IPR/CBM practice became available on 2012-09-16. A defendant receiving a demand letter citing this patent is not facing a "hardened" or "narrowed" asset — they are facing a patent that has been unenforceable for over a century.

No proceedings to enumerate

There is no proceeding to list, and I will not manufacture one. For completeness, the two public-search hits that look like this patent are false positives arising from number fragments, not from US 7,268,99:

Neither implicates Arthur Bloyd Gahagan's agitator. Web searches for US726899 PTAB, for the patent title combined with IPR, and for litigation/CAFC activity all returned zero results tied to this patent.

Strategic summary

Claim status: no claims are canceled, none are sustained, all are untested — because no tribunal has ever had a reason to test them. US 7,268,99, "Agitator for oil-wells," was filed 1902-04-29, granted 1903-05-05, and carried a 17-year term under the then-governing statute, expiring 1920-05-05 (Google Patents records the corresponding legal-status event on that date; the ODP ingest shows no post-1920 activity of any kind). The original assignee of record was John A. Hughes, with one-half interest assigned by Gahagan per the specification's headnote — that is a 1902-era assignment, not a current holder, and the "Current Assignee: JOHN A. HUGHES" field on Google Patents should be read as a stale artifact of the original assignment record rather than an assertion of present ownership. Claims 1–8 exist on paper and were never construed, tested, or invalidated by any body.

Estoppel landscape: there is none, and § 315(e)(2) has never attached. No petitioner has ever been a party to an IPR on this patent, so no petitioner, real party in interest, or privy is estopped as to any ground. That said, the practical effect is the same as blanket estoppel: every prior-art ground is "available" in the abstract, but none is useful, because the defensive posture you want is not a § 102/§ 103 attack — it's the expiration date. Separately, two of the three AIA trial vehicles are categorically unavailable here: PGR reaches only patents claiming priority to an application filed on or after 2013-03-16, and CBM reaches only patents claiming financial-services data-processing subject matter. Only IPR is theoretically filable against an expired patent, and in this instance there is no economic or legal predicate for one.

Pattern signals: absent by construction. There is no repeat petitioner (there is no petitioner), no patent-owner appellate aggressiveness (the Federal Circuit did not exist until 1982, and the CAFC has never seen this patent), and no defensive aggregator such as Unified Patents in the chain. The only "pattern" is that the patent predates the entire modern patent-challenge apparatus. I want to flag the framing in the task prompt explicitly: the observation that "well-asserted patents eventually attract IPRs" is sound as a general heuristic, but a 1903 patent with a 1920 expiration is the canonical exception, not a weak instance of the rule. Do not counsel a client that the absence of PTAB activity here means the patent is untested-but-serious.

Recommended next steps

• If you are a defendant: do not spend a dollar on an IPR, and do not treat this as a merits fight. The dispositive fact is the 1920-05-05 expiration. Under 35 U.S.C. § 286, damages reach only six years back from suit — a window that closed in 1926. There is therefore no live infringement theory, no injunctive exposure, and no royalty base. Verify the asserted patent number character-by-character against the demand letter: given how often "726"/"899" fragments collide with unrelated patents (see the two false positives above), the single highest-probability explanation is a transcription or citation error in the letter, and the real patent at issue is a different one — likely a live, modern patent. Demand the full patent number, issuance date, and claim chart before responding on the merits.
• Preserve the record. If a demand letter genuinely cites US 7,268,99 with a 1903-05-05 issuance date, that is a facially baseless assertion. Retain the letter, envelope, and any claim chart; a pre-suit declaratory-judgment posture or a Rule 11 / state unauthorized-practice inquiry may be appropriate, but those are judgment calls to make with litigation counsel after the identity of the patent is confirmed.
• If active proceedings are pending: none are, so there are no institution deadlines, no oral-hearing dates, and no statutory one-year FWD clock to track. Nothing is on the PTAB's calendar.
• If someone asks whether to file defensively: the answer is no. IPR against an expired, unassertable patent would burn fees to obtain a cancellation with no practical effect on any infringement exposure.

Sourcing note: the Google Patents record for US 7,268,99 (https://patents.google.com/patent/[US726899](/patent/US726899)/en) is the authoritative document here and is internally consistent on the 1902-04-29 filing / 1903-05-05 grant / 1920-05-05 expiration timeline; the USPTO ODP structured block reports no AIA trial proceedings; and independent web searches for PTAB and Federal Circuit activity returned no results attributable to this patent. I found no proceeding, no decision, and no docket number to link to — and I am stating that as an absence of evidence that in this instance is strong, rather than filling the gap with the similarly-numbered proceedings that did surface.

Inventors

Arthur Bloyd Gahagan — sole named inventor. Residence at filing: Glade Mills, Butler County, Pennsylvania (a Butler County oil-field community). Employer at the time of filing: not determinable from the record — the patent is filed as an individual, unassigned application (Serial No. 105,191, "No model"), with no corporate co-assignor on the face of the instrument. Butler County was in the heart of the Pennsylvania oil region in 1902, and the specification's framing of the device as "a fitting or attachment which is connected to the ordinary construction of suction-pipes in oil-wells" is the language of a field operator/machinist rather than a manufacturer's in-house engineer, but that is inference, not record evidence.

Pattern check — no departure/fire-sale pattern: Gahagan filed at least one sibling application in the same period, US 715,253 ("oil-well pump"), bearing the identical witnesses J. N. Cooke and L. T. Marks (see the printed specification at https://patentimages.storage.googleapis.com/4d/bc/6b/d60c63ce9bcbeb/[US715253](/patent/US715253).pdf). Two same-witness filings from one small-town inventor indicate a single local patent solicitor handling a personal, unincorporated docket — not an inventor cohort exiting a corporate assignee within 12 months of filing. The "all inventors departing the assignee" tell is not present; there was no assignee at filing.

Original assignee

There is no corporate original assignee. The patent issued to Gahagan as inventor, who assigned one-half interest to John A. Hughes, of Glade Mills, Pennsylvania — a co-ownership split recited on the printed patent itself ("ASSIGNOR OF ONE-HALF TO JOHN A. HUGHES, OF GLADE MILLS, PENNSYLVANIA"). Google Patents' "Current Assignee: JOHN A. HUGHES" field (https://patents.google.com/patent/[US726899](/patent/US726899)/en) reflects that on-face half-interest and nothing more — it is not derived from a recorded post-issuance assignment.

• Primary line of business: not a commercial entity. Both named parties are individuals resident in the same oil-town; the half-interest is characteristic of early oil-field practice, where a working inventor partnered with a local backer or co-operator.
• Product embodying the claims: no evidence located of either party manufacturing or selling the agitator. The disclosure is written as a retrofit attachment for "the ordinary construction of suction-pipes," i.e. field installation rather than factory production. Unclear / no evidence found.
• Current status: moot. The patent was granted 1903-05-05, subject to a 17-year term, and Google Patents records the anticipated expiration as 1920-05-05, status "Expired - Lifetime." Any ownership question lapsed over a century ago. No successor entity, bankruptcy, or acquisition record exists in any indexed source I located.

Assignment timeline

No recorded assignments exist for US 726899 — stated plainly.

Searches of the USPTO Assignment Center (https://assignmentcenter.uspto.gov/) and its predecessor interface (https://assignment.uspto.gov/patent/index.html) surface no reel/frame entries for this patent, and no third-party index reproduces any. The determinative reason is structural, not evidentiary: the USPTO's searchable assignment database "contains all recorded Patent Assignment information open to the public from August 1980 to the present." US 726899 was filed 1902-04-29, granted 1903-05-05, and expired 1920-05-05 — sixty years before the digital recording window opens. Whatever paper assignments may have been executed and recorded in the 1902–1920 period are not in the searchable system and were not located in any indexed secondary source.

Consequently:

• Reel/Frame: none. No correspondent of record, no repeat-player attorney, and no chained assignees can be identified because there is no chain to reconstruct.
• The only ownership division of record is the on-face half-interest to John A. Hughes, effected by the printed patent and the original assignment filed with the 1902 application — not a post-issuance reel/frame recording.
• Google Patents "Legal Events" for this patent list only the 1902 filing, the 1903 grant, and the 1920 expiration. No reassignment, security interest, merger, name change, license, or release events appear.

Per the rubric, with no records and only the original filing-stage assignment, the outcome is Insufficient data; I am stopping the analysis here rather than speculating about a chain that the record does not contain.

I'll research this patent through multiple searches.

The second search returned a false match I need to flag. Let me dig deeper.

Prior-Art Analysis — US Patent No. 726,899

A. Target patent confirmed (not a look-alike)

The patent is a pre-1952 (pre-AIA) oil-field mechanical patent with 8 claims, all in combination form: "In an agitator for oil-wells, the combination with the working barrel, of a coupling connected to said working barrel and having a receiving-chamber surrounding the same provided with sprayer-jets leading therefrom, said coupling having a valve-controlled passage-way therein communicating with said receiving-chamber, and revoluble means for opening and closing said passage-way…"

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B. ⚠️ Identifier collision — do not merge these

My search for the literal string "726899" returned a second, unrelated record: a 1968 application Serial No. 726,899 that issued as US 3,511,149 (optical/recording subject matter). That is an application number collision, not the patent at issue. US 726,899 (1903) ≠ US 3,511,149 (1970). Per the strict-identifier rule I am flagging this rather than folding it into the analysis. Nothing from US 3,511,149 is prior art to, or relevant to, US 726,899.

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C. Critical threshold finding: US 726,899 has no prior-art citations of record in the retrieved record

The authoritative full text and Google Patents record for US 726,899 contains:

• No "References Cited" section
• No "Patent Citations" (Citations) section
• No "Cited By" section
• Only a "Similar Documents" block, plus machine-generated "Prior art keywords" (coupling, oil, valve, sleeve, working) and CPC classification F04B 47/02.

This is the honest answer to the question as posed: there is no set of examiner citations to walk through. "Similar Documents" on Google Patents is an algorithmic similarity list generated from modern classification/text comparison — it is not a citation of record, was not cited by the examiner or applicant in 1902–03, and carries no legal weight as "prior art of record." I am treating it as a lead list, explicitly labeled as such, and then adding prior art I found by independent search.

Statutory note (important): 35 U.S.C. § 102 did not exist in 1902. The governing law was R.S. § 4886 (as amended), which barred a patent where the invention was known or used by others in the U.S., or patented or described in a printed publication anywhere, before the inventor's invention, or more than two years before the application date (i.e., before April 29, 1900). Applying the modern § 102(a)/(b) labels below is a translation device, not a literal statement of 1902 law.

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D. "Similar Documents" (algorithmic leads — NOT citations)

D-1. Pre-dating the April 29, 1902 filing (potential prior art)

D-2. Post-dating the filing (legally unavailable as anticipatory art)

US 928,639 A (1909-07-20, Deep-well pump) · US 958,862 A (1910-05-24, Pump for wells) · US 1,086,050 A (1914-02-03, Oil-well cleaner and agitator) · US 1,347,806 A (1920-07-27) · US 1,561,768 A (1925-11-17) · US 1,766,487 A (1930-06-24) · US 1,944,573 A (1934-01-23) · US 1,959,621 A (1934-05-22) · US 2,205,739 A (1940-06-25) · US 2,342,485 A (1944-02-22) · US 2,461,512 A (1949-02-15) · US 2,905,250 A (1959-09-22) · US 2017/0247989 A1 (2017-08-31).

These can only serve as background evidence of the art; they cannot anticipate under any § 102 subsection. US 1,086,050 ("Oil-well cleaner and agitator") is a title near-twin of the patent at issue but post-dates it by 11 years and is therefore irrelevant to validity — the reverse relationship (726,899 as art against 1,086,050) is the direction that would matter.

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E. Additional prior art located by independent search (not in the Similar Documents list)

Two pre-1902 references surfaced through full-text searching that are more substantively on-point than most of the list above:

E-1. US 202,570 — Nathan S. Minniss & David A. Wray, "Improvement in Methods of and Apparatus for Obtaining Oil from Oil-Wells," granted April 16, 1878; applied for October 4, 1877.
Disclosure (verbatim from the specification): "consists in agitating the oil in oil-bearing sand, at or near the bottom of the well, in such manner as to prevent the clogging of the veins or pores with paraffine, heavy oil, &c., to facilitate the escape of gas and increase the yield of oil." The device uses rods/rope/wire armed with pivoted agitating wings, arms, or beaters on a stem, rotated or reciprocated from the surface. This anticipates the stated problem and purpose of US 726,899 almost word-for-word (Gahagan's object: prevent "thickening of the oil, thereby clogging the strata").
Claim relevance: Potentially relevant to the preamble/generic purpose of all claims 1–8 — but it discloses no coupling, no sprayer-jets, no valve-controlled passage-way, and no revoluble sleeve. It cannot anticipate any claim as written.

E-2. US 391,431 — Ralph Shoff, "Device for Cleaning Oil-Wells and Promoting the Flow of Oil," granted October 23, 1888; applied for November 10, 1887.
Disclosure: a coupling (2) on oil-well tubing leading to an enlarged tube/casing (3) forming an annular chamber, containing a valve-casing (5) with a spring-seated valve (8) having a beveled edge (9) seating on a beveled valve-seat (10); oil/gas pressure lifts the valve to discharge accumulated oil. This is the closest structural analogue found to the "coupling … having a valve-controlled passage-way therein" element of claim 1.
Claim relevance: Potentially relevant to claim 1's coupling + valve-controlled passage + surrounding chamber concept. It does not disclose sprayer-jets, a revoluble element, a screw-threaded sleeve, or seating/unseating by rotation — so it does not anticipate any of claims 1–8 in full, though it is the strongest § 103-type/obviousness candidate.

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F. Claim-by-claim § 102 assessment

Every claim 1–8 is a combination claim requiring, at minimum: (i) a working barrel; (ii) a coupling connected to it; (iii) a receiving-chamber surrounding the working barrel; (iv) sprayer-jets leading from that chamber; and (v) a valve-controlled passage-way communicating with the chamber. Claims 3–8 add a revoluble sleeve and/or a seat below the passage-way; claims 5 adds screw-threads; claims 6–8 add engagement by the working-valve mechanism and structure permitting its withdrawal.

Bottom line: On the evidence retrieved, no reference anticipates any of claims 1–8. The distinct combination — a working-barrel-surrounding spray chamber with jets, closed by a screw-threaded revoluble sleeve driven by rotation of the working-valve mechanism itself through its leather cups, with a cooperating liner/prong arrangement (21/22/23) for valve withdrawal — is not disclosed in any single reference located. The strongest invalidity theory available is a pre-1952 "invention"/obviousness attack (Hotchkiss v. Greenwood standard, i.e., lack of the exercise of the inventive faculty) combining US 414,464 or US 391,431 (valve + chamber in well tubing) with US 202,570 (bottom-hole agitation to prevent clogging) — not § 102 anticipation.

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G. Limitations on this analysis — stated explicitly

1. No citations of record exist for US 726,899 in the retrieved record. Anything labeled "prior art" above is either (a) a Google machine-generated "Similar Documents" lead, or (b) a reference I located by independent search. Neither category is a legal citation.
2. I did not retrieve the full disclosure text of US 414,464, US 425,624, US 430,919, US 639,601, US 320,176, US 241,039, US 209,258, US 143,345, US 44,587, US 55,816, US 110,930, or US 246,692 in this session. Their entries above rest on title and grant date only; the descriptions I give for US 414,464 are inferences from its title and must be verified against the specification before any legal reliance.
3. Full text was obtained only for US 202,570 (Minniss & Wray, 1878) and US 391,431 (Shoff, 1888), plus the target patent itself.
4. US 108,605 A / US 110,930 A entries in the Similar Documents list are partially garbled by OCR ("Henry millingar," "Charles w") and are unidentified as to subject matter.
5. The claim text of US 726,899 as published is OCR-degraded (claim 8 in particular is run together with fragments of claim 6). Element-by-element comparisons should be re-run against the patent PDF (patentimages/US726899.pdf) before being relied upon.
6. This is a technical prior-art survey, not a legal opinion or a validity determination.

I'll ground this analysis by pulling what I can on the prior-art references listed on the page.

Obviousness Analysis — U.S. Patent No. 726,899 (Gahagan, "Agitator for Oil-Wells")

Note on scope and sourcing before I begin. This analysis uses the reference list that appears on the Google Patents page for US726899 under its "Similar Documents" heading, together with the "Prior art keywords" field (coupling, oil, valve, sleeve, working) and the specification's own admissions. I was able to retrieve actual text for four of the pre-1902 references: US 430,919 (Campbell & Pickett, 1890), US 425,624 (O'Neil, 1890), US 320,176 (Sanner, 1885), plus adjacent, closely-related contemporaneous art (US 391,431 (Shoff, 1888), US 642,012 (Shaw, filed 1899, issued 1900), US 34,444). I could not retrieve the disclosures of US 414,464, US 639,601, US 209,258, US 44,587, US 143,345, US 110,930, US 241,039, US 246,692, or US 55,816. Where my analysis depends on a reference I only have by title, I say so explicitly rather than assume its content.

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1. Correction to the prior sections (contradiction flagged)

Two points require flagging per the instruction to build on prior sections without repeating them:

1. The earlier litigation summary mischaracterized the status of the "prior art" references. It stated: "The prior-art references in the specification, e.g., US 414,464 and US 430,919, are the examiner's/field citations." On the face of the source page, that is not correct on either count. (a) Neither reference appears in the specification text. The specification contains no citation to any patent; its only references are to the "ordinary foot or stand valve," the "ordinary working-valve mechanism," and the "ordinary construction of suction-pipes." (b) US 414,464 and US 430,919 appear only in the page's machine-generated "Similar Documents" list, which is a relevance ranking that (as shown below) mixes in references published long after the 1902 filing date. Calling these "examiner's/field citations" overstates their provenance. They are legitimate prior art on their own dates, but they are not admitted prior art and not necessarily anything the examiner considered.

2. Date discrepancy. This task states the current date is April 26, 2026; the system header states September 28, 2026. Nothing in this analysis turns on the difference, but the inconsistency is noted. (The prior litigation section's list already includes a case filed January 20, 2026, which is consistent with either date.)

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2. Governing legal framework (and an important caveat for a 1903 patent)

• Filing/priority date: April 29, 1902 (application Serial No. 105,191). Issued May 5, 1903. Anticipated expiration May 5, 1920.
• Prior art cutoff. For §103 purposes, a reference must qualify under the conditions of patentability in effect for that filing. Only references published before April 29, 1902 (in practice, dated more than one year before, or at minimum before the filing date) are usable.
• §103 framework. The four Graham v. John Deere Co., 383 U.S. 1 (1966) factors: scope and content of the prior art; differences between the prior art and the claims; level of ordinary skill; and secondary considerations. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) supplies the "expansive and flexible" approach and forecloses rigid "teaching, suggestion, motivation" formalism — motivation may come from the design incentive, market demand, or the nature of the problem itself.
• MATERIAL CAVEAT — pre-1952 "invention" standard. US 726,899 issued under the Patent Act of 1870/1897, and §103 of the 1952 Act was intended as declaratory of existing law (Graham, 383 U.S. at 17). For patents granted before the 1952 Act, the courts of that era (and some later ones) applied a heightened "invention" standard, crystallized in Cuno Engineering Corp. v. Automatic Devices Corp., 314 U.S. 84, 91 (1941) ("flash of genius") and Great Atlantic & Pacific Tea Co. v. Supermarket Equipment Corp., 340 U.S. 147 (1950) (a combination of old elements must produce "a new or different function" / more than an "aggregation" to be patentable). A modern §103 analysis of this patent therefore understates the intellectual-property hurdle the 1903 court would have applied; a finding of "obvious" under Graham/KSR is a necessary but not always sufficient condition to invalidity for a patent of this vintage. I flag this because it materially affects the reliability of any "would have been obvious" conclusion here, and it is the single strongest shield against invalidation of US 726,899.

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3. Person of ordinary skill in the art (PHOSITA), c. 1902

A machinist or mechanical engineer in the Pennsylvania oil fields (Warren/Butler/McKean counties — the same region that produced O'Neil, Sanner, Shaw, and Campbell & Pickett) who designed and serviced sucker-rod pumping equipment. There is direct record evidence of this skill level and of the art's self-identification: Shaw (US 642,012, filed Sept. 12, 1899) claims his disclosure "will enable others skilled in the art to which it appertains to make and use the same"; O'Neil (US 425,624) describes "the well-known mode of increasing the flow of the well by forcing compressed air into the pump-tubing"; Campbell & Pickett (US 430,919) describe the well-tube as "formed in sections and connected in the manner well known in the art." Such a person knew, as a matter of course: working barrels/tubing, standing (foot) valves, working valves with cages and leather cup packing, sucker/polished rods, pipe unions and couplings, and screw-threaded sleeve adjustments.

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4. Admitted prior art in the specification itself

Independent of the "Similar Documents" list, the patent admits the following into the prior art by its own words:

This matters: the patent's own characterization concedes that the working barrel, coupling, standing valve, working valve, cup packing, and rod are all old. The only asserted contribution is the revoluble sleeve valve that gates flow from the coupling interior into a surrounding spray chamber fitted with jets (plus the prong-and-seat arrangement for valve withdrawal). Obviousness therefore turns almost entirely on that one sub-combination.

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5. Reference-by-reference assessment

5.1 US 430,919 — Campbell & Pickett, "Oil-Pump," issued June 24, 1890 (filed Jan. 13, 1890) — primary reference

This is the most damaging reference, and I retrieved its actual text. Its stated purposes are:

"…whereby the paraffine, with which the oil-rock or sand soon becomes coated, may be dissolved and removed by spraying or flooding it with oil."

"After a well has been pumped for a certain period the oil-producing rock or stratum frequently becomes coated with parafine… To effect this we raise the lower or standing valve by means of the connecting-rod, whereby the oil in the tube rushes down through the valve-seat, and, being retained by the check-valve 22, it is forced up through the smaller tubes 24 and ejected through the perforations 25 therein, whence it is sprayed over the parafine, which is dissolved and removed thereby."

It also discloses: well-tube 1; sucker/polished rod 2; upper working valve 4 with cage 5 and check-valve 6; annular packings 7 on tubular section 8; a sleeve or union 9 with apertures 10; lower/standing valve with elongated tubular portion 16 seating on valve-seat 17 in an enlarged section 18 with enlargement 19 and a check-valve 22 positioned below the standing valve; and nozzles/perforations 25 for spray distribution. Independently, its second stated object is: "the upper and lower valves may be so connected together that when repairs are needed in the lower valve it may be removed, together with the upper valve, by means of a simple sliding or other connection, and the necessity thereby avoided of removing the tubing from the well."

Mapping to US 726,899:

Where it diverges from claim 1: the actuator is linear (raising the standing valve via the connecting rod), not "revoluble." That is the single genuine gap.

5.2 US 320,176 — Sanner, "Pump for Oil-Wells," June 16, 1885 — secondary reference

Retrieved full text. Sanner's barrel A has a side chamber d bored into a bulged portion of the barrel, "that connects with the interior of the barrel or the tube a by an opening, e, below the valve," with a tube f extending up and perforated to admit oil, and the standing valve c seated in tube a. This is a chamber formed in/around the barrel, fed through a passage below the standing valve, with a perforated tube — structurally the same genus as the coupling 1 / chamber 9 / passage-way 18 / jets 11 arrangement of US 726,899. Sanner's stated motivation is gas exclusion, not spraying, but the structural teaching (side chamber on the barrel fed below the standing valve) is squarely in the same art and the same pumping string.

5.3 US 425,624 — O'Neil, "Ejector for Oil-Wells," Apr. 15, 1890

Retrieved full text. Discloses a packing device 8 (disk 9 with beveled top surface + rubber gasket 10) inside the tubing, and a cooperating beveled ring 11 on the inner tube that seats on the gasket to form "an efficient air and oil tight joint," performing a sealing/compartmentalizing function between an oil zone and an upper chamber. Relevant for the beveled face-against-beveled-seat sealing concept (Gahagan's inclined face 20 on sleeve 19 engaging inclined seat 20′), and for the general practice of a machined beveled ring seating on a packing/gasket in a well string.

5.4 US 391,431 — Shoff, "Device for Cleaning Oil-Wells and Promoting the Flow of Oil," Oct. 23, 1888 (found in the same search space; not on the subject page's list)

Discloses a casing containing a valve with an adjustable seat pressure, using an adjusting-screw 14 bearing on a follower 13 to vary spring tension on valve 8, and an enlarged tube 3 creating an annular space around an inner valve-casing, with radial arms 6. Two teachings are relevant: (i) the annular/chamber-around-a-central-flow-element geometry, and (ii) the screw-threaded adjustment of a valve element, which is the evidentiary bridge to "revoluble means."

5.5 US 642,012 — Shaw, "Bailer or Pump," issued Jan. 23, 1900 (filed Sept. 12, 1899)

Discloses a valve-casing with "an upwardly extending screw-threaded reduced portion, as at 7, which engages internal threads in the lower end of the tube" — i.e., a screw-threaded sleeve/casing retained within and adjusted relative to a surrounding tubular member, in an oil-well pump. Time-stamped after the 1902 Gahagan filing, so it is not §103 prior art here; I cite it only as evidence of what was conventional (and as a caution against using it in a real invalidity contention).

5.6 US 34,444 (found in the search results, earlier date)

Discloses a hollow piston-rod with a ring k′ having screw-threads cut in it, "so as to take the upper end of the upper ring f of the lower valve-seat, so that when it is desired to draw out the lower valve-seat b from the pump it may be done by screwing the ring k′ on the ring f and raising the two valve-seats together by means of the piston-rod." This is direct prior art for claims 6–8's concept: a screw/threaded engagement of a member at the top of a sleeve with the rod/valve assembly to permit withdrawal of valve mechanism with the rod. I could not confirm its issue date from the retrieved fragment; treat as fully reliable only after a date check.

5.7 US 414,464 — "Combined valve and spraying apparatus for cleaning oil-wells," Nov. 5, 1889

I retrieved no text for this reference; my search for it returned US 391,431 (Shoff) instead. On its face and date it sits in the same art and is the closest analog on the "combined valve + spraying in an oil well" concept. I cannot state its disclosure with confidence and do not rely on it. In any real invalidity opinion it would be the first document to pull in full.

5.8 References that are NOT prior art — do not use

The "Similar Documents" list is date-agnostic. The following are post-1902 and cannot be used against US 726,899: US 1,086,050 (1914), US 928,639 (1909), US 958,862 (1910), US 1,347,806 (1920), US 1,561,768 (1925), US 1,766,487 (1930), US 1,944,573 (1934), US 1,959,621 (1934), US 2,205,739 (1940), US 2,342,485 (1944), US 2,461,512 (1949), US 2,905,250 (1959), and US 2017/0247989 A1. Notably, US 1,086,050 ("Oil-well cleaner and agitator," 1914), though topically the closest title on the page, is 12 years too late. Any obviousness statement that cites it is defective as to this patent.

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6. Claim-by-claim obviousness mapping

Claims 1 and 2 — the broad chamber/jet/valve-revoluble claims

Proposed combination: Campbell & Pickett (US 430,919) in view of Sanner (US 320,176).

Differences from the prior art: the claims require (a) a chamber surrounding the working barrel with jets leading out, (b) a valve-controlled passage-way connecting the coupling interior to that chamber, and (c) revoluble means to open and close that passage-way. Campbell & Pickett supply (b) and the spray function, and supply the "oil forced to perforations/jets and sprayed" result. Sanner supplies (a) — a chamber formed on the barrel fed through an opening below the standing valve. What remains is only the rotary actuator.

Motivation to combine:

1. Identical field and identical problem. Both are cased-hole oil-well pump fittings; both are addressed to deposition/clogging of the oil-producing formation. Campbell & Pickett: "the oil-producing rock or stratum frequently becomes coated with parafine… it is necessary, and is usually a material benefit to the well, to remove this parafine." Gahagan: air acting on the oil-bearing strata "causes a thickening of the oil, thereby clogging the strata and seriously diminishing the pumping capacity thereof." KSR expressly recognizes that "the improvement is not a matter of design choice if the prior art teaches that the same problem is solved in the same way," and that a known problem, long felt, in a crowded art supplies motivation.
2. Same string, same tool. Campbell & Pickett already teaches the sprayer/nozzle idea in the same tubing; Sanner already teaches a barrel-mounted side chamber fed below the standing valve. A PHOSITA seeking to locate a spray chamber below the working barrel (as Gahagan's preamble requires) would naturally mount it as a chamber/coupling on the barrel as Sanner does, rather than add a separate pipe.
3. Reasonable expectation of success. Both references show operable hardware in production wells; no new principle is required. The combination is a rearrangement of known well-string components.
4. The patent's own admissions eliminate most of the claim: coupling, working barrel, stand valve and working valve are conceded to be "ordinary."

The real weak spot — "revoluble means." Neither verified reference uses a rotary actuator; Campbell & Pickett's valve is lifted linearly by the connecting rod, and O'Neil's and Sanner's are passive/pressure-operated. A rigorous analysis must therefore find a separate source for "revoluble means for opening and closing said passage-way": Shoff's adjusting-screw 14 acting on follower 13 (US 391,431, 1888) shows screw-threaded rotary adjustment of a valve element in an oil-well tool; Shaw (US 642,012) shows a screw-threaded sleeve engaging internal threads in a well-pump tube (but is post-1902 and thus unusable); US 34,444 shows screw-threaded engagement of valve-seat rings to withdraw valves by the rod. On the pre-1902 record available to me, I can say the rotary-actuator limitation is the one element for which the showing is thin. A §103 conclusion on claims 1–2 is strong but not airtight without a verified pre-1902 reference teaching a rod-rotated threaded sleeve valve seated in a well-pump coupling.

Claim 2 is a fortiori obvious if claim 1 is. Claim 2 differs from claim 1 only by the words "within said coupling" ("revoluble means within said coupling for opening and closing said passage-way"). A revoluble sleeve that opens and closes a passage-way formed in the coupling is, in the disclosed and claimed structure, necessarily located within the coupling. Claim 2 adds no structural or functional limitation of independent patentable weight, and is invalid on the same record and for the same reasons as claim 1. This also raises a §112(b)/claim-distinctness problem for the patentee (the two claims are not distinctly different inventions), but that is outside the §103 question.

Claims 3, 4, 5 — the seat + sleeve + screw-thread sub-combination

Proposed combination: Campbell & Pickett + Sanner + Shoff (US 391,431) / the general screw-threaded-sleeve art (e.g., US 34,444).

Claim 3 adds "said coupling… provided with a seat below the same, and a revoluble sleeve within said coupling adapted to close and open said passage-way by the engaging and disengaging of the same with said seat." Claim 4 adds a "sleeve connected to said coupling" plus "means for turning said sleeve." Claim 5 adds that the sleeve engages "by screwthreads" with the coupling.

• The seat below the passage-way is symmetry with the admitted standing-valve seat 6′ and with O'Neil's beveled ring 11 seating on a beveled disk/gasket below the flow passage (US 425,624), and with Sanner's opening e below the valve feeding the side chamber.
• The screw-threaded sleeve undergoing rotary motion to seat/unseat is a classical stop-valve/needle-valve/packing-sleeve expedient. Shoff's adjusting screw (US 391,431) and US 34,444's threaded ring k′/ring f show screw-threaded, rotation-driven engagement of closure members in this exact art. A PHOSITA would have recognized that replacing Campbell & Pickett's linear valve-lift with a threaded sleeve gives positive locking, fine axial adjustment, and a metal-to-metal seal — a predictable mechanical advantage with a reasonable expectation of success (KSR; Agrippa).
• Note the functional wording. "Means for turning said sleeve" in claims 4 and 5 is purely functional and, in the specification, is disclosed only as the friction of the working-valve leather cups 29 against the sleeve interior. A claim to any "means for turning" is broader than the disclosed frictional structure and therefore covers every known rod-rotation mechanism in a well string — a breadth that makes it easier, not harder, to establish obviousness, and simultaneously raises a written-description/enablement question.

Claims 4 and 5 differ by one word ("screwthreads"). If claim 5 is obvious, claim 4 (broader) is necessarily obvious; the patentee cannot save claim 4 by narrowing to claim 5. Claim 5 is the narrowest of the three and thus the hardest to invalidate — the correct target in an invalidity contention is claim 3, then 4.

Claims 6, 7, 8 — sleeve engaged by the working valve + withdrawal projections/ring

Proposed combination: Campbell & Pickett + Sanner + the valve-withdrawal art (US 430,919's own sliding connection; US 34,444's threaded ring engagement).

Claims 6–8 add: a sleeve engageable by the working-valve mechanism to open and close the passage-way, plus "means at the top of said sleeve" / "a ring between said working barrel and coupling having projections thereon adapted to fit within seats in the interior of said sleeve to permit the easy withdrawal of the working-valve mechanism from said sleeve."

• The "engageable by the working-valve mechanism" feature is directly taught by Campbell & Pickett, whose entire second object is a connection between the working valve and the lower valve actuated by the sucker/polished rod, and which expressly achieves the same functional result — service or operate the lower apparatus without pulling the tubing.
• The withdrawal projections/prongs feature is the mechanical equivalent of the sliding connection in Campbell & Pickett (rod 13 with head/nipple 14 captive in tube 12) and of the threaded ring k′/ring f engagement in US 34,444 ("so that when it is desired to draw out the lower valve-seat… it may be done by screwing the ring k′ on the ring f and raising the two valve-seats together by means of the piston-rod"). A ring with prongs fitting into seats is an obvious, predictable alternative to a sliding head-and-nipple or a threaded ring for the same stated purpose — a mere substitution of one known coupling/engaging expedient for another, yielding no new function (A&P Tea, 340 U.S. at 152; KSR).
• Motivation: the express, decades-old commercial need to service the lower valve without pulling the tubing — stated in Campbell & Pickett in 1890 and again in Gahagan in 1902 — is exactly the long-felt need that supplies the reason to combine. Both references are directed to it.
• Claim 7 is a near-duplicate of claim 6 (the "means… at the top of said sleeve" vs. "means between said working barrel and top of said sleeve"), and claim 8 restates claims 6–7 with the ring/prong structure made explicit. The three claims rise and fall together to the extent they recite the same function; claim 8 is the most specific and thus the most defensible, claim 6 the broadest and most vulnerable.

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7. Secondary considerations (Graham factor 4)

• Long-felt, unresolved problem. Air ingress → oil thickening → clogged strata was known and costly ("seriously diminishing the pumping capacity"); the art had been attacking paraffin/thickening/sand clogging since at least 1864 (US 44,587), 1885 (Sanner), 1888 (Shoff), 1890 (O'Neil, Campbell & Pickett), and 1900 (Shaw). This is a crowded art — the classic KSR / A&P Tea circumstance in which a new assembly of old elements is viewed with suspicion.
• No evidence of unexpected results in the specification. The stated operation (oil rises from the stand valve into the coupling, passes through the passage-way, lifts ball-valve 15, enters chamber 9, sprays through jets 11) is precisely the ordinary sequence of a lifted valve feeding a nozzle — no superior or surprising property is asserted.
• No commercial-success or copying evidence is available on this record. If a patentee advanced nexus-backed commercial success, licensing, or copying, that could rebut. Nothing in the material supplied supports it.
• The pre-1952 "invention" standard (§2 caveat above) is the counterweight: a Cuno/A&P Tea court might find these claims, especially claims 5 and 8, exhibited more than "aggregation." That is a genuine and non-trivial defense.

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8. Bottom line

The single reference a real invalidity analysis must obtain in full is US 414,464 (Nov. 5, 1889, "Combined valve and spraying apparatus for cleaning oil-wells"). Its title alone covers the heart of claims 1–2 and it predates the Gahagan filing by thirteen years; if it discloses a valve-gated spray path in a well coupling, claims 1–2 may be anticipated under §102 rather than merely obvious under §103. I could not retrieve it in this session and expressly do not rely on its content.

Do not cite, in any invalidity contention against this patent: US 1,086,050 (1914), US 928,639 (1909), US 958,862 (1910), US 1,347,806, US 1,561,768, US 1,766,487, US 1,944,573, US 1,959,621, US 2,205,739, US 2,342,485, US 2,461,512, US 2,905,250, or US 2017/0247989 — all post-date the April 29, 1902 filing.

Confidence: High on the qualification of US 430,919 (I retrieved its full text; its paraffin-spraying and tubing-sparing valve-connection teachings are verbatim and directly on point), US 320,176, US 425,624, and on the element-by-element mapping of the admitted prior art. Moderate on the completeness of the pre-1902 rotary-actuator showing. Low on the content of US 414,464, US 639,601, US 209,258, US 44,587, US 143,345, US 110,930, US 241,039, US 246,692, and US 55,816, which I did not retrieve and whose disclosures I decline to characterize.