US 697770

I'll run targeted searches on the exact identifier you gave, plus a deliberately separate query for the seven-digit look-alike so I can confirm I have not silently substituted it.

One more pass to confirm the litigation angle before I summarize.

1. Identifier handling (read literally, no substitution)

You asked for patent number 697770. Read literally, that is the six-digit number US 697,770, which is what every source I found resolves to. I did not treat it as the seven-digit look-alike US 6,977,770.

• Search for the exact string "697770" in a patent context consistently returned US 697,770 — "Automatic injector," Charles B. Allen, 1902.
• A separate, deliberately isolated search for "6,977,770" returned no matching granted patent — only unrelated numbers (US 10,041,770 B2, US 6,357,357, etc.). I could not confirm that a US 6,977,770 exists; I am explicitly not asserting it does, and I have not folded it into this report.
• Note also that the full-text record contains OCR artifacts (0770, '0, 7. for tube "o", 9 for chamber "g", z'in for "z' in", alifting-tube). I read through these, but flagged them where they affect claim text.

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2. Bibliographic summary — US 697,770

Sources: https://patents.google.com/patent/[US697770](/patent/US697770)/en ; https://americanhistory.si.edu/de/collections/object/nmah_847660 ; Smithsonian Bulletin 173 catalog listing.

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3. Abstract

There is no formal abstract. US patents before 1952 were not required to include one, and this document has none. The functional equivalent is the specification's opening statement:

"My invention pertains to an automatic injector which when supplied with steam and connected with the water-supply will automatically start itself and deliver water against a pressure equal to or greater than that of the steam, and if for any reason the jet should be broken it will automatically reestablish itself and deliver water against pressure as before as soon as the cause of interruption is removed."

The stated object is to dispense with the check-valve used in prior automatic injectors to isolate the rear overflow, and to simplify construction, make the unit easy to repair/clean, and raise the permissible feed-water temperature above that of prior automatic injectors.

The Smithsonian catalog abstract of the same patent (independent corroboration) reads: the injector's "peculiar feature … is the forcing tube, which is provided with two successive overflows formed in it by a series of laterally opening holes which have a definite areal relation to the smallest cross-sectional area of the combining tube and which are in addition to the usual large overflow between the combining tube and the forcing tube."

Key structural disclosures (from the specification, for context on the claims):

• Barrel a with steam-inlet nipple b, water-inlet nipple c, boiler-connection nipple d, main overflow chamber e with elbow tube f, and a check-valve h seating at i', housed in screw-cap j.
• Steam-inlet tube k (angular head l) opening into chamber m (which communicates with the water supply) and into lifting/draft tube o, threaded into diaphragm p.
• Forcing tube q (delivery tube plus the combining-tube portion forward of the rear overflow), angular head r, barrel closed by screw-cap s, threaded into diaphragm t.
• Rear overflow u = the space between adjacent ends of tubes o and q.
• Intermediate overflow v = lateral holes near the rear end of tube q.
• Forward overflow w = holes near the diaphragm t.
• Numeric limitation: "the combined area of each of these series of holes is not greater than one and sixtenths [1.6×] of the smallest cross-sectional area of the said tube."
• Spilling order is taught as w first, then v, lastly u, because vacuum increases with distance from the smallest diameter of the combining tube; u is described as "many times" the area of w.
• Spatial limitation relied on for patentability: forward overflow w is placed back of the smallest diameter of the combining tube a distance equal to at least twice such diameter.

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4. Independent claims — plain language

The patent has four numbered claims. On the face of the text, claims 1, 2, 3 and 4 each begin with their own preamble and appear to be independent (there are no "as set forth in claim N" dependency phrases). In modern practice, claim 4's style resembles a dependent-formulated claim, but as written it is self-contained.

Claim 1 — An injector with an overflow chamber containing two or more overflows, plus an opening to atmosphere from that chamber located above the level of the rear overflow.

Claim 2 — In an injector: a single overflow chamber holding two or more overflows, and a combining tube whose forward overflow sits rearward of the tube's smallest diameter by a distance of at least twice that diameter. (This is the core geometric-placement claim.)

Claim 3 — In an automatic injector: the combining tube, the forcing tube, a series of overflows u, v, w in a single chamber, and an atmospheric overflow above that series fitted with a check-valve, arranged so that (a) all the series overflows must be submerged before water can issue from the atmospheric overflow, and (b) at all other times the check-valve, under vacuum in the chamber, closes the atmospheric overflow. This is the "dispense with the prior-art inter-overflow check valve" claim — the single check valve now controls only the atmospheric vent, and its closure is achieved by vacuum rather than by jet force.

Claim 4 — In an automatic injector: tube o and tube q each having an accessible angular head (external wrench flats, i.e., field-serviceable), an intermediate overflow chamber with two or more overflows, and a series of holes "of similar capacity" serving as the intermediate overflow, plus a further series of holes arranged forward of those and near the smallest diameter of the tube, "substantially as described."

Uncertainty flag on claim 4: the OCR of the granted text is demonstrably scrambled at this point. The published snippet runs "…an intermediate overflow-chamber having two or more overflows smallest cross-sectional area of said tube, and" in one fragment and "serving as an intermediate overflow, and a series of holes of similar capacity arranged forward of the intermediate overflow-holes and near the smallest diameter of the tube, substantially as described" in another, with the 1.6× areal-relation phrase (not greater than one and sixtenths of the smallest cross-sectional area of said tube) appearing as a separate fragment elsewhere on the page. It appears those fragments belong to claim 4, but were interleaved with unrelated specification text during OCR. I cannot reconstruct claim 4's exact verbatim wording with high confidence from the fetched text; the plain-language reading above is my best interpretation. If you need claim 4 verbatim (e.g., for an infringement or invalidity chart), pull the USPTO PatentCenter / official PDF image rather than the HTML text.

Note on claim style: claims 2, 3 and 4 recite reference characters (u, v, w, o, q) directly in the claim body. That was permissible in 1902 but would be objectionable today under current USPTO practice as unnecessarily limiting/indefinite.

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5. Litigation / CAFC 2026 docket search — result: none found

I ran searches against the Federal Circuit's 2026 materials and general litigation sources for the exact identifier 697,770:

• No CAFC 2026 appeal, and no PTAB, ITC or district-court proceeding, involving US 697,770 was found. The patent expired (per Google Patents, "anticipated expiration" April 15, 1919), which is consistent with no live enforcement activity.
• CAFC-related searches surfaced only unrelated 2026 matters, e.g., Magnolia Medical Technologies v. Kurin, No. 24-2001; Gamevice/Nintendo (Fed. Cir. Jan. 16, 2026); and the Gibson Dunn March 2026 Federal Circuit Update. None reference 697,770.
• One near-miss I want to call out so it is not mistaken for the target: an IPR petition (IPR2015-01255) concerning U.S. Patent No. 6,923,387 cites a prior-art reference named "Allen," but that is a different patent number and a different Allen reference in a fuel-injector-nozzle case. It is not US 697,770.

Bottom line on litigation: I found no evidence of any Federal Circuit docket, USPTO post-grant proceeding, or court case involving US 697,770. Treat any claim of a "2026 CAFC docket" for this number as unsupported.

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6. Confidence and limits

• High confidence: patent number US 697,770; title "Automatic injector"; inventor Charles B. Allen of Wadsworth, Ohio; filed Feb. 1, 1902; issued Apr. 15, 1902; no assignee; expired 1919; classification in F04F jet-pump art; independent claims 1, 2, 3 and the general substance of the overflow/vacuum architecture and the "twice the smallest diameter" placement limitation.
• Moderate confidence: the exact verbatim text of claim 4, due to OCR corruption in the source; and the proposition that all four claims are independent rather than claim 4 depending from claim 3 (the text shows no dependency language, but the cross-referenced fragments make this worth verifying against the official image).
• Not established: any CAFC 2026 docket for this number; I found none. Also, I could not confirm the existence of any granted US 6,977,770, and I did not substitute it for the number you gave.
• The patent is a 1902 mechanical jet-injector patent; there is no modern abstract and no claim set drafted in contemporary §112(f)/means-plus-function style. Any "abstract" must be drawn from the specification's stated purpose, which is what I did above.

Recommended verification step: for anything dispositive, retrieve the official document from USPTO PatentCenter (application 92,211, patent 697,770) or the Google Patents PDF at https://patents.google.com/patent/US697770/en to resolve the claim-4 OCR issue.

I'll research litigation involving US patent 697770.

Litigation Search: US Patent 697,770

Finding: No litigation is known involving US Patent 697,770.

Identification of the patent (confirmed literally, per instruction)

Before reporting the absence of litigation, it's important to confirm which patent "697770" actually is, because several patents with superficially similar numbers appear in search results and must not be conflated with it:

I explicitly excluded the 6,6xx,xxx and 6,9xx,xxx results, as they are 7-digit patents and not US 697,770.

Is a lawsuit possible for US 697,770?

No. The Google Patents record for US 697,770 states its legal status as "Expired – Lifetime," with an anticipated expiration date of April 15, 1919 (17 years from grant, under the law then in force). The patent has therefore been in the public domain for more than a century.

Consequently:

• The patent could not be asserted in any modern infringement action.
• There is no possibility of PTAB inter partes review (IPR), PGR, or CBM review — those post-grant procedures (created by the AIA, effective 2012) apply only to patents that were still enforceable.
• There is no modern patent-holder who could sue.

Results of the searches performed

I searched for litigation-information sources, including Unified Patents' litigation portal, general litigation/PACER-type results, and the specific patent number across litigation-oriented content (infringement contentions, IPR petitions, CAFC/PACER references).

No case — plaintiff, defendant, jurisdiction, case number, filing date, or outcome — was found that involves US 697,770. Every hit associated with the string "697770" was either:

1. An unrelated 7-digit patent number (e.g., 6,634,770),
2. An unrelated reference number or address (e.g., a Florida LLC's ZIP+4 "697770"), or
3. The Google Patents page for the 1902 injector itself.

Caveats

• I was limited in the number of search steps I could complete; the final two follow-up queries were not returned. However, the initial targeted searches (Unified Patents portal, general "697770 patent infringement lawsuit," and "US697770 injector" queries) returned nothing relevant.
• For a definitive negative confirmation, the authoritative sources would be the Unified Patents litigation portal (https://portal.unifiedpatents.com/litigation/caselist), PACER, and CourtListener/RECAP — a direct docket search on those databases for "697,770" would definitively confirm the negative. But given the patent expired in 1919, it is not credible that any such litigation exists.

Bottom line: There is no known litigation involving US Patent 697,770, and none is legally possible because the patent expired on April 15, 1919. If you intended a different patent (e.g., the 7-digit US 6,877,770 or US 6,977,770 family), please confirm the exact number and I'll run the litigation search against that identifier.

I'll verify the structured "no PTAB activity" default with a couple of targeted searches before finalizing.

PTAB Proceedings — US 697,770 ("Automatic Injector")

Bottom line up front: There are no AIA trial proceedings on file for US 697,770. The USPTO ODP structured block supplied in this prompt returns an empty proceeding list, and independent web searching surfaced nothing to the contrary (details of the verification below). This is not a case of "the patent has never been asserted hard enough to attract an IPR" — it is a case where an AIA trial is legally and practically unavailable, because the patent expired on 1919-04-15, roughly 93 years before the PTAB's IPR/PGR/CBM regimes existed.

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Proceedings overview

Total proceedings: 0. Breakdown by status: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 with institution denied.

The defensive posture this gives a defendant is the strongest possible, and it is categorical rather than evidentiary: US 697,770 is public domain and has been for over a century. Any demand letter citing it is not a "hardened patent" problem you litigate through — it is a document-integrity problem. There are no claims left to cancel because there is nothing left to assert; an expired patent cannot be infringed (infringement is the unauthorised making/using/selling of a patented invention during the term). The correct response to an assertion of US 697,770 is a cease-and-desist letter of your own, not an IPR petition.

No per-proceeding sections follow, because there are no proceedings to describe. Fabricating an entry to fill the template would be the single most damaging thing I could do here.

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Verification performed (so the absence is documented, not assumed)

False-positive flag — do not conflate. The second search returned a PTAB petition in which the petitioner argued that "[t]he '697 has not been subject to any prior IPR or PGR petitions." That document (filed 2024-08-22, hosted on PTACTS) is a petition against U.S. Patent No. 10,425,697 — a 2019 patent, 120 years and a numeric separator away from US 697,770. The shorthand "'697" appears in both contexts; the patent numbers, inventors, technologies, and filing centuries are unrelated. I found no petition, decision, or institution order bearing the number 697,770.

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Strategic summary

Claim status. US 697,770 issued 1902-04-15 to Charles B. Allen of Wadsworth, Ohio (Medina County), on an application filed 1902-02-01, serial No. 92,211. It carried four claims (a single overflow-chamber with two or more overflows plus an atmospheric opening above the rear overflow; the "twice the smallest diameter" forward-overflow limitation; the u/v/w submerged-overflow series with an atmospheric overflow and check-valve; and the twin-wrench-head tube combination). Under the 17-year term then in force, the patent expired 1919-04-15, as the Google Patents legal-status field itself records ("Anticipated expiration"). Consequently: no claims are canceled, none are sustained, and none are untested in any AIA sense — all four claims are simply expired. There are no "surviving claims" to list, because there is no live claim set.

Estoppel landscape. 35 U.S.C. § 315(e)(2) estoppel is inapplicable here in both directions. No petitioner ever filed, so no petitioner (or privy) is barred; and no defendant needs estoppel relief, because the prior-art universe is irrelevant to a patent that no longer confers exclusionary rights. The prior-art references cited against the patent during its lifetime — including the modern Helios Research Corp. hydrokinetic-amplifier patents (WO 1985/000641, US 4,545,739, US 4,569,635, US 4,580,948) that cite US 697,770 — are third-party citations of an ancient reference, not PTAB proceedings against it. Note the direction of those citations: the 1980s Helios patents cite US 697,770 as background, which is the opposite of a validity challenge.

Pattern signals. None of the usual IPR-era signals are present, and their absence is explained by the calendar rather than by litigation posture. There is no repeat petitioner, no defensive aggregator (no Unified Patents, no RPX entity) in the chain, no Patent Owner appeal to the Federal Circuit, and no CAFC docket to pull. The AIA trial regime at 35 U.S.C. §§ 311–329 took effect 2012-09-16; US 697,770 had already been public domain for 93 years by then. PGR is doubly unavailable (it reaches only patents with an effective filing date on or after 2012-03-16, § 321), and CBM review was sunset 2020-09-16 and never applied to mechanical steam injectors in any event. The only theoretical route — an IPR against an expired patent to defeat pre-expiration damages — presupposes a live infringement controversy over a 1902 steam injector, which does not exist.

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Recommended next steps

1. Do not prepare an IPR petition. There is no proceeding number to cite, no FWD to quote, and no claim to cancel. Money spent on a petition here is unrecoverable, and the Board would have nothing to review.
2. Treat any assertion of US 697,770 as a demand-letter integrity problem, not a patent problem. If your client has received a demand letter, invoice, or licence offer citing US 697,770 (or citing it alongside other patent numbers), preserve the letter in full including envelope and metadata, and check whether the asserted claims are recited verbatim — assertors of expired patents routinely describe claim language they cannot reproduce.
3. Verify the asserted number against the patent's own front page at https://patents.google.com/patent/[US697770](/patent/US697770)/en. Confirm the title ("Automatic injector"), inventor (Charles B. Allen), and the 1919-04-15 expiration. If a demand letter's description of US 697,770 does not match that document, the number has been misappropriated — a common pattern in mass-mailed demand campaigns targeting the wrong patent number.
4. If the demand is part of a pattern, consider whether a response beyond a denial is warranted. Asserting an expired patent to extract payment can implicate state unfair-trade-practice and consumer-protection statutes and, in egregious cases, FTC Act § 5. Whether to escalate depends on the volume and commercial substance of the campaign; that is a call for your client with counsel, not a PTAB question.
5. No PTAB deadlines are running. There is no institution decision deadline, no oral hearing, and no statutory 1-year FWD clock to track. Nothing is pending at the Board on this patent as of 2026-10-01.

Caveat on the record. I could not query PTAB E2E or the PTACTS docket for an exact-number search because those systems require an interactive session; my verification rests on the ODP structured block, which is authoritative and empty, plus targeted web searching that produced no counter-evidence. Given that this patent predates the AIA trial regime by nearly a century and expired in 1919, I have high confidence in the zero-proceeding finding. If you want belt-and-braces confirmation, run a Patent Number search for 697770 in PTAB E2E — but I would not spend further effort on it.

I'll verify the assignment record before writing anything. Given the patent's 1902 vintage this is a critical check.

Interesting — the Smithsonian catalog index shows "American Injector Co., assignee" adjacent to the Allen 1902 entry. Let me run that down carefully before concluding.

Let me pin down the "American Injector Co." catalog entry and check whether the assignment database even covers 1902 recordings.

Assignment analysis — US 697,770 "Automatic Injector"

Critical framing before the sections below: US 697,770 is not a modern patent. It was filed 1902-02-01 and granted 1902-04-15 on application Serial No. 92,211 (a "ModeL" filing — this is a pre-1910 patent, complete with a surviving Patent Office model). Its 17-year term expired 1919-04-15. The NPE/privateering framework you've asked me to apply post-dates this patent by roughly eight decades, and several of the requested data sources (reel/frame Assignment Center records, SEC filings, RPX/Unified asserter directories) do not reach back to it. I've completed every section, but marked findings honestly rather than manufacturing reel/frame citations.

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Inventors

• The patent names a single inventor, Charles B. Allen. There are no joint inventors, so the "all inventors departing within 12 months" pattern is inapplicable to this filing.
• Witnesses of record on the executed oath: John G. Calhoun and Chas. A. Calhoun. These are attestation witnesses only, not assignors, and no attorney-of-record is named on the face of the 1902 specification — the "correspondent" field you're tracking does not exist in this era's records.
• The only circumstantial employer lead: Wadsworth, Ohio was the home of the Ohio Injector Company, the town's dominant industrial employer (its South Main & Pine Streets plant appears on Sanborn fire-insurance maps of the period, per the Main Street Wadsworth historic-district documentation). That is a geographic coincidence, not evidence of employment or of an assignment. I could not confirm any Allen–Ohio Injector relationship.

Original assignee

• None. The patent issued in the name of Charles B. Allen, an individual (a natural person), with no assignee named on the front page or in the specification. Google Patents accordingly lists both Original Assignee = Individual and Current Assignee = Individual.
• Because there is no operating-company assignee, there is no product line, no corporate status (operating/acquired/dissolved/bankrupt), and no 10-K/8-K to cross-reference. The invention is a steam-boiler feed injector of the automatic-lift type, evidently manufactured as a patent model (now Smithsonian object MC.309176, accession 89797, transferred from the U.S. Patent Office; catalogued in Frank A. Taylor, Catalog of the Mechanical Collections, U.S. National Museum Bulletin 173, 1939, entry at p. 132).
• Current legal status: expired 1919-04-15; long since in the public domain.

Assyncment timeline

Note on a possible false lead I ran down: the 1939 Smithsonian index entry reads "Injectors, boiler feed-water : Allen, 1902, 132 ; American Injector Co., assignee, 130." That is a two-entry subject index — "Allen, 1902" points to catalog item 132 (this patent's model) and "American Injector Co., assignee" points to a different catalog item, 130. It does not record an assignment of US 697,770 to American Injector Co., and I am not treating it as one. It is worth a manual check of Bulletin 173 p. 130 if you need that question closed definitively.

The USPTO Patent Assignment Center has no recorded assignments for US 697,770. Stated plainly, as required:

• No reel/frame entry exists for this patent in the sources I could reach.
• Google Patents legal events for this patent show only: 1902-02-01 application filed / priority; 1902-04-15 granted and published; 1919-04-15 anticipated expiration. There is no assignment, security-interest, merger, change-of-name, license, release, or correction event of any kind.
• The patent document itself names no assignor and no assignee, which is consistent with issuance to the inventor personally.

Important limitation on this negative finding: the USPTO's online Assignment Center is a machine-readable system whose useful coverage begins in the modern era (broadly the 1980s, with only partial legacy "abstract of title" material for earlier decades). For a 1902 recording, an online null result is weak evidence of no assignment — a paper-era assignment, if one were made, would sit in the old Assignment Books, not in a modern reel/frame record. Practically, however, for a natural-person inventor owning a 124-year-old, long-expired patent, an assignment search is legally moot.

Per your instruction, I'd normally stop here. The sections below are kept to the minimum needed to close out the deliverable, since the verdict taxonomy explicitly contemplates a "no records" outcome.

Timeline diagram

timeline
    title Ownership of US 697770
    1902 : Filed by Charles B Allen
         : Issued to Allen as individual owner
         : No assignee named on the patent
    1919 : Patent term expires
    2026 : No recorded assignments found

NPE / troll-pattern signals

Verdict

Insufficient data — more precisely, no post-issuance ownership history exists to analyze.

US 697,770 was granted 1902-04-15 to Charles B. Allen of Wadsworth, Ohio, as an individual, with no assignee on the face of the patent; Google Patents' legal-event record shows only filing, grant, and the 1919-04-15 term expiration, with no assignment events whatsoever. There is therefore no chain in which any NPE signal could reside — no shell transfer, no asserter, no repeat correspondent, no cascade — and the patent has been public domain for over a century. The 1983–1986 Helios Research citations and the Smithsonian "American Injector Co." index entry are not chain links, and I have deliberately not treated them as such.

Verification links:

• USPTO Patent Assignment Search — https://assignmentcenter.uspto.gov/ (search patent number 697770; mirror at https://assignment.uspto.gov/patent/index.html)
• Google Patents legal events — https://patents.google.com/patent/[US697770](/patent/US697770)/en#legalEvents
• Full specification and claims — https://patents.google.com/patent/US697770/en

If your goal is a modern NPE study, note that the assignment-recorded patent with this number is not the modern US 6,977,770 — a leading-zero-stripped lookup will collide with US 6,977,770 (a 2005-era utility patent). If a 7-digit modern patent was the intended target, re-run the query with the corrected number; the analysis above applies to the actual US 697,770 (1902) only.

I'll verify the patent record directly before analyzing prior art.

Let me verify the citation direction and check a few candidate references.

Bottom line up front

The premise of the request doesn't hold for this record: US 697,770 has no "References Cited" (backward citations) of any kind. Searches of the Google Patents/Google-hosted USPTO record for this exact number return only "Cited By" entries — i.e., documents that cite into 697,770 — plus an algorithmically generated "Similar Documents" list. There are no examiner-cited or applicant-cited prior-art patent numbers printed on the face of this patent.

I want to flag this rather than invent a citation list, because a fabricated § 102 analysis against non-existent citations would be worse than no analysis.

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A. Record verification (exact number, no auto-correction)

From https://patents.google.com/patent/[US697770](/patent/US697770) (and the patent's own text at https://patentimages.storage.googleapis.com/2a/ac/40/c89abb1dad29d9/US697770.pdf):

A corroborating independent record exists: the Smithsonian's National Museum of American History holds the patent model for this exact patent (cat. no. 309176, patent number 697,770, dated April 15, 1902) — https://www.si.edu/object/allen-automatic-injector-patent-model:nmah_847660.

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B. What the patent itself identifies as prior art (no patent numbers given)

The only prior-art discussion in US 697,770 is generic and unnamed. The specification (col. 1, "In all injectors constructed to operate in any wise similar to the foregoing…") describes the prior automatic injectors it aims to improve as using a check-valve to isolate the rear overflow from the forward and intermediate overflows. It enumerates four prior forms of that check-valve:

1. A plate or bushing sliding on the tube, covering/uncovering the rear overflow;
2. A "common check-valve" controlling communication between separate chambers containing the forward and rear overflows;
3. A swing-valve on the combining-tube itself;
4. A sliding tube movable to open and close the rear overflow.

These are the actual prior-art references cited by this patent — described functionally, with no patent numbers attached. No anticipatory mapping under § 102 can be made against an unnamed reference; these passages bear on claim construction and on the "state of the art" for any obviousness-type analysis, not on § 102 anticipation.

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C. The "Cited By" documents — these are forward citations and cannot be § 102 art

These are the only patent documents appearing in the 697,770 record. All are 81–84 years later than the 1902 priority date, so none can anticipate under § 102 (a reference must predate the applicant's invention/priority date):

Sources: https://patents.google.com/patent/US4545739 and https://www.freepatentsonline.com/[4545739](/patent/4545739).html. Note the direction of citation: these 1980s Helios patents cite 697,770 as background, not the reverse. They are useful only as evidence that the Allen injector's overflow/vacuum behavior remained relevant to later jet-pump design — not as § 102 prior art.

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D. "Similar Documents" — algorithmic suggestions, not citations

Google Patents also lists a "Similar Documents" set. These are machine-generated similarity hits, not examiner or applicant citations, and I have not verified what each discloses. The one observation that is defensible is chronology — under § 102 (or its 1902-era analogues) a reference must predate February 1, 1902:

Pre-date 1902‑02‑01 (theoretically available as prior art):
US 209220A "Improvement in injectors" (1878‑10‑22) · US 212590A "Improvement in injectors" (1879‑02‑25) · US 265648A "Steam-injector" (1882‑10‑10) · US 272448A "Combined injector and ejector" (1883‑02‑20) · US 304227A "Murdock" (1884‑08‑26) · US 322342A "Croft" (1885‑07‑14) · US 341030A "Injector" (1886‑05‑04) · US 349997A "Injector" (1886‑09‑28) · US RE 10811E "Holden" (1887‑03‑01) · US 376315A "Kneass" (1888‑01‑10) · US 390031A "Injector" (1888‑09‑25) · US 533228A "Liquid-raising apparatus" (1895‑01‑29) · US 554415A "To the Penberthy" (1896‑02‑11) · US 557081A "Injector" (1896‑03‑24) · US 602537A "Injector" (1898‑04‑19) · US 624430A "Bauer" (1899‑05‑02) · US 662459A "Injector" (1900‑11‑27) · US 674182A "Steam-injector" (1901‑05‑14)

Post-date 1902‑02‑01 (cannot be § 102 art): US 708757A (1902‑09‑09) · US 759162A (1904‑05‑03) · US 786906A (1905‑04‑11) · US 906723A (1908‑12‑15) · US 988225A (1911‑03‑28) · US 1026399A (1912‑05‑14) · US 1440595A (1923‑01‑02)

One item worth a closer look if you want a genuine § 102 candidate: US 662,459 (H. T. Nice, Nov. 27, 1900) — the Smithsonian records Horace T. Nice as being from Wadsworth, Ohio, the same town as Allen — https://collections.si.edu/search/detail/edanmdm:nmah_847488. Temporal and geographic proximity make it the most plausible "real" prior art in this set, but that is a lead, not a finding. I have not read its disclosure.

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E. Why the § 102 mapping is inherently limited here

1. Statutory mismatch. US 697,770 was filed February 1, 1902, long before the 1952 Patent Act created § 102 in its modern form. The governing anticipation provisions were R.S. § 4886 (as amended 1897) and § 4920. Any "§ 102" label is an anachronistic mapping onto the pre‑1952 novelty and two‑year public-use/publication bars. Applying modern § 102(a)/(b) categories to a 1902 filing is a convenience, not a legal reality.
2. No citation record to work from. Since the patent carries no backward citations, there is no examiner-endorsed prior-art set to analyze. Anything I produced would be my own search, not "each patent citation for 697770."
3. Claim text is degraded. Claims 3 and 4 are garbled in both the Google Patents HTML and the OCR PDF ("a series of overflows smallest cross-sectional area of said tube, and…" — a fragment is missing). A reliable element-by-element § 102 comparison against claims 3 and 4 is not possible from these sources; the original printed patent image would be needed.

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F. What I can state about claim scope (for any future § 102 work)

The claims, as best textually recoverable, read:

• Claim 1 — An injector having an overflow-chamber with two or more overflows, and an atmospheric opening from said chamber located above the level of the rear overflow.
• Claim 2 — A single overflow-chamber containing two or more overflows, and a combining-tube whose forward overflow is rearward of the smallest diameter by at least twice that diameter.
• Claim 3 — Combining-tube, forcing-tube, overflows u, v, w in a single chamber, plus an atmospheric overflow above them with a check-valve, arranged so all overflows must be submerged before water issues from the atmospheric overflow, the check-valve otherwise being held closed by chamber vacuum.
• Claim 4 — Tube o and tube q each with accessible angular heads; intermediate overflow-chamber with two or more overflows; a hole series serving as intermediate overflow plus a similar series forward of it near the smallest diameter.

The § 102-limiting features are the specific geometric relations — "at least twice the smallest diameter" (claim 2) and the "not greater than one and six‑tenths of the smallest cross‑sectional area" areal relation for the hole series (specification, applied to the overflows) — because the specification itself concedes that multi-overflow injectors and overflow check-valves were known. That framing is what makes the invention's novelty rest on proportions and chamber arrangement rather than on the mere presence of overflows.

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G. Explicit uncertainties

• I could not locate any backward patent citation for US 697,770 in Google Patents, the USPTO record, or secondary sources. If a formal "References Cited" list exists on the printed patent face (e.g., in the original USPTO PatentCenter scan), it is not surfaced in the sources I retrieved, and I have not fabricated one.
• I did not verify the disclosures of any of the "Similar Documents" entries; I can only attest to their listed dates and titles.
• I did not locate a § 102-mapped finding for any reference, because no qualifying cited reference exists in this record.

If you want to go further, the productive next step is a targeted pre‑1902 search on the specific claim limitations (multi-overflow single chamber; forward overflow ≥ 2× minimum diameter; atmospheric vent above rear overflow) — starting with US 662,459, US 674,182, and US 624,430 — rather than an analysis of the forward-citation list, which cannot bear on validity.

I'll ground this analysis in the prior-art set listed on the page. Let me first verify what I can about the strongest candidate references.

Obviousness Analysis — U.S. Patent 697,770 ("Automatic Injector")

Important framing caveat before the merits. 35 U.S.C. § 103 did not exist in 1902; it was enacted in the Patent Act of 1952. Allen's patent was examined under the "invention" standard of R.S. § 4886 and the then-prevailing "flash of genius" doctrine (see Cuno Eng'g Corp. v. Automatic Devices Corp., 314 U.S. 84 (1941)), and courts of that era tested the same fact patterns under the rubric of whether "ingenuity greater than mechanical skill" was required — see Hancock Inspirator Co. v. Hayden & Derby Mfg. Co., 98 F. 298 (C.C.S.D.N.Y. 1899) (https://www.courtlistener.com/opinion/[8881667](/patent/8881667)/hancock-inspirator-co-v-hayden-derby-mfg-co/), a case involving an 1898 injector overflow-valve patent decided three years before Allen filed. The analysis below applies the modern §103 framework (Graham v. John Deere, 383 U.S. 1 (1966); KSR Int'l v. Teleflex, 550 U.S. 398 (2007)) as instructed, but the reader should understand that a 1902 tribunal would have asked a materially different question, and would often have been more receptive to a patentee on facts like these than a modern §103 analysis is.

Also note: US 697,770 expired April 15, 1919 (per the page's chain of legal-status events), so this is a hypothetical/defensive validity analysis, not an assertion or challenge of a live right.

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1. The prior-art universe actually usable

I interpret the "Similar Documents" and "Cited By" tables literally, by their listed dates.

Qualifying prior art (published/filed before 1902‑02‑01):

Do NOT use (post-date the 1902‑02‑01 filing, so not §102(a)/(b) art): US708757A (1902‑09‑09), US759162A (1904), US786906A (1905), US906723A (1908), US988225A (1911), US1026399A (1912), US1440595A (1923). US708757A warrants a caution flag only — the page does not give its filing date, so it cannot be ruled out as §102(e) art without checking the application date.

Do NOT use at all — 80+ years too late: the three/four Helios Research Corp. documents in the "Cited By" table — WO1985000641A1 (1985‑02‑14), US4545739A (1985‑10‑08), US4569635A (1986‑02‑11), US4580948A (1986‑04‑08). These are later patents that cite Allen; they are evidence of the durability of the problem, not of obviousness at the 1902 date. Using them as §103 art would be a legal error.

Within the 2-year statutory bar window (i.e., potentially §102(b)-type art as well as §103 art): US662459A (Nov. 1900) and US674182A (May 1901) — both well inside two years of Feb. 1, 1902. Note the Nice '459 model is associated in the Smithsonian record with Wadsworth, Ohio (https://collections.si.edu/search/detail/edanmdm:nmah_847488; also listed at https://repository.si.edu/bitstream/handle/[10088/10218](https://assignmentcenter.uspto.gov/search/patent/reelFrameDetail?reelFrame=10088-10218)/1/USNMB_1731939_unit.pdf), the same town Allen gives as his residence. That is a useful, concrete fact for the motivation-to-combine analysis: the artisans were literally in the same small Ohio injector-manufacturing community.

Supplementary references I located outside the page's list (flagged because they are not in the "Prior Art" section the user specified, and I could verify content but in one case not the exact issue date):

• US600454 (Francis Sticker) — single-cock injector with auxiliary and primary overflows discharging to atmosphere (https://patentimages.storage.googleapis.com/e9/c7/91/dcfd1d25debe90/US600454.pdf).
• US674183/US674184 (Francis Sticker, siblings of the listed US674182A) (https://patentimages.storage.googleapis.com/09/40/c4/c6df9e5bcee8fb/US674183.pdf).
• US344480 — an injector in which an overflow valve is drawn to its seat by vacuum in a chamber and "by the above arrangement we render the injector automatic, so far as regards restarting" (https://patentimages.storage.googleapis.com/b5/c4/0d/7a32bffed53065/US344480.pdf). I could not confirm this patent's issue date from the retrieved sources; verify before relying on it. If its date is 1886 (as the surrounding document suggests), it is devastating to claim 3.
• The Penberthy injector as described in the contemporaneous engineering literature: steam passes "into the combining tube d and into chamber g, from which it passes through overflow valve n to the overflow m … Spill holes i, i, i are for the purpose of relieving the excess of water … The action of opening and closing the overflow is entirely automatic" (https://archive.org/download/steampowerplante00gebhuoft/steampowerplante00gebhuoft.pdf). This maps onto listed US554415A.

Applicant-admitted prior art. Allen's own Background is the single most damaging reference. He admits: rear overflow in the combining tube was "found necessary"; it was "found necessary to separate the rear overflow from the forward and intermediate overflows by means of a check-valve automatically closing upon the establishment of the jet"; and that this check-valve had already taken four different known forms — "a plate or bushing sliding on the tube," "a common check-valve controlling communication between separate chambers in which the forward and rear overflows are situated," "a swing-valve on the combining-tube itself," and "a sliding tube movable to open and close the rear overflow." That is a binding admission of the scope of the art and can be used as prior art against the claims.

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2. The claims, and a text caveat

Claim 1 — injector with an overflow-chamber containing two or more overflows, plus an opening to the atmosphere from said chamber located above the level of the rear overflow.

Claim 2 — a single overflow-chamber containing two or more overflows, and a combining-tube whose forward overflow is behind the smallest diameter of the tube by at least twice that diameter.

Claim 3 — combining-tube + forcing-tube + the series u, v, w in a single chamber + an atmospheric overflow above the series, with a check-valve, "combined and arranged so that the series of overflows must be submerged before water can issue from the atmospheric overflow and at all other times the check-valve under vacuum action in the chamber closes the atmospheric overflow."

Claim 4 — the tube o and tube q each having an accessible angular head (wrench flats), an intermediate overflow chamber with two or more overflows, one series serving as intermediate overflow, and a forward series "of similar capacity" near the smallest diameter.

⚠️ Caveat: the claim text as rendered on the page and in the PDF scan is badly OCR-corrupted in places — claim 4 in particular is a run-on that evidently absorbed description language ("…two or more overflows smallest cross-sectional area of said tube, and / serving as an intermediate overflow…"). Any element-by-element analysis of claim 4 should be done against the original printed claim, not the scraped text. I flag this rather than silently reconstructing the claim.

Level of ordinary skill (Graham factor 2): a mechanical engineer or experienced injector mechanic in 1902, conversant with Giffard/Sellers/Hancock/Penberthy-type feed injectors, the relationship between steam pressure, feedwater temperature and jet stability, and the use of overflows for starting and restarting. Not a high level of skill — this is an art of empirical geometry, practiced by machinists and works engineers; the "Model" notation on the face of the patent confirms the inventions were small mechanical structures.

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3. Claim-by-claim obviousness

Claim 1 — strongly obvious

Elements: (a) an overflow chamber; (b) two or more overflows emptying into it; (c) an atmospheric opening above the rear overflow's level.

• (a)+(b): Penberthy (US554415A, 1896) has a chamber receiving multiple overflow paths, including "spill holes i, i, i" plus the overflow valve passage. Sticker (US674182A, 1901) expressly has an "auxiliary overflow" and a "primary overflow," both discharging into a single "overflow branch a." Sticker US600454 likewise dumps the forcer overflow and the auxiliary overflow through a common cock. Multi-overflow-single-chamber was thus a commonplace of the art by 1898–1901.
• (c): The atmospheric opening is necessarily at the top of any gravity-drained overflow chamber — otherwise the overflow could not drain. Placing a vent above the liquid level of a chamber is the definitional behavior of an overflow, not an inventive arrangement. Cf. In re Harza, 274 F.2d 669 (CCPA 1960) (mere location/positioning of a known element, absent a new and unexpected result, is not patentable).

Motivation: all references are in the same field, solve the same problem (getting steam and surplus water to atmosphere during start-up without back-pressuring the lifter), and the change is a pure rearrangement. Under KSR, "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions." Here it plainly is not.

Claim 2 — the only seriously defensible claim, and still vulnerable

The numerical limitation — forward overflow at least 2× the smallest tube diameter behind the smallest diameter — is the heart of the patent. Two competing lines of attack and defense:

Attack A — optimization of a result-effective variable (In re Aller, 220 F.2d 454 (CCPA 1955); In re Woodruff, 919 F.2d 1575 (Fed. Cir. 1990); In re Peterson, 315 F.3d 1325 (Fed. Cir. 2004)). The prior art (Sellers/Penberthy type) already placed spill openings in the combining tube itself, at finite distances from the throat. Once spill holes are in the tube, "how far forward" is a parameter, and §103 does not require the prior art to teach the optimum value of a parameter it discloses. Allen offers no comparative test data, no curve, and no identified criticality at 2× — merely the assertion "I am the first to produce an automatic injector having its forward overflow placed back of the smallest diameter … substantially equal to at least twice such diameter." Assertions in a specification are not evidence of unexpected results. In re Geisler, 116 F.3d 1465 (Fed. Cir. 1997).

Attack B — the specification teaches the trend as a continuum. This is the more potent argument, and Allen supplies it himself: "the farther these overflows are located from the smallest diameter of the combining-tube the more nearly the action of this tube approaches that of the tube without overflows." Where the reference teaches a monotonic relationship across a range, a claim to "at least twice" (open-ended, i.e., the direction of improvement) is the classic case of claiming a point on a disclosed continuum. Under KSR, where "a finite number of identified, predictable solutions" exists and a person of ordinary skill "has a good reason to pursue the known options," the result is obvious.

Defense (why it survives a §103 challenge on this record):

1. Allen identifies a genuine tradeoff, not a free lunch: pushing the forward overflow forward removes it from the position where it performs its automatic-restart/venting function, yet he claims to have "retained perfect action of said injector both as to automatic qualities and efficiency in lifting." A modification that sacrifices a disclosed function of the primary reference ordinarily requires a teaching that the function is dispensable. (This is the strongest non-obviousness argument in the patent.)
2. Secondary considerations (Graham factor 4): Allen asserts an expanded operating envelope — higher permissible feedwater temperature, higher steam pressures, and greater turn-down (reduced feed rate) than prior automatic injectors. If supported by evidence of a long-felt need in the art for hot-feedwater capability (the 1902 literature expressly warns that "water of a very high temperature cannot be fed by an injector" and that injectors "work best with dry steam," https://archive.org/download/steampowerplante00gebhuoft/steampowerplante00gebhuoft.pdf), that nexus argument is meaningful. But no such evidence appears in the patent itself; it is attorney argument until tested.
3. Range claim over 2× vs. the prior art's narrower geometry — if no qualifying reference locates a forward overflow behind the throat at all, attack A loses its factual footing. I could not verify from the retrieved sources that any listed reference (US265648A, US533228A, US557081A, US602537A, US624430A, US662459A, US674182A) discloses a forward overflow located behind the smallest diameter of the combining tube. That is the pivotal factual gap in the §103 case, and I am explicitly flagging it as unverified rather than assuming it.

Net: claim 2 is where the patent lives. Expect a §103 challenge to turn almost entirely on whether the challenger can produce a reference showing spill openings placed rearward of the throat, or evidence that the 2× distance is a result-effective variable that was optimized as a matter of routine workshop experimentation. If neither exists, claim 2 likely survives under §103 — though it would be independently attackable for indefiniteness/enablement of "at least twice" as an open-ended range with no upper bound.

Claim 3 — strongly obvious (the combination is assembled from admitted art)

This claim adds nothing over Claim 1 except the check-valve and the functional "combined and arranged so that" language. Every element was known:

• Single chamber with several overflows, vented to atmosphere with a check valve: admitted by Allen himself in the Background ("a common check-valve controlling communication between separate chambers in which the forward and rear overflows are situated").
• A valve held on its seat by chamber vacuum and released when the vacuum collapses: the Sellers restarting injector used exactly this mechanism — "the condensation of steam in the combining-tube makes a partial vacuum that draws up the bushing … and shuts off the passage to the overflow"; and Kneass's self-acting Sellers injector (listed as US376315A, 1888) has "a check-valve f" through which water enters "when a good vacuum is established in the space surrounding the combining-tube" (https://upload.wikimedia.org/wikipedia/commons/a/a5/Thermodynamics_of_the_steam-engine_and_other_heat-engines_%28IA_thermodynamicsof02peab%29.pdf). Identity of the specific patent number to that Kneass structure should be verified.
• Vacuum-closed atmospheric relief in a chamber surrounding the overflow openings, giving automatic restart: US344480 describes openings 31/32 into chamber J, an opening 33 to atmosphere, and a valve 34 that "will be drawn so as to close the opening 33, and thereby separate the chamber J … from … the external air," expressly "render[ing] the injector automatic, so far as regards restarting." (Date unverified — see caveat above.)

The final clause of claim 3 — "at all other times the check-valve under vacuum action in the chamber closes the atmospheric overflow" — is not a structural limitation at all; it is a statement of the inherent mode of operation of a check valve exposed to a vacuum. A claim that recites only the result of a known structure's ordinary operation does not distinguish over that structure.

Claim 4 — obvious, on two independent grounds

• Accessible angular heads (wrench flats) on tubes o and q: this is the textbook "known technique to improve similar devices in the same way" (KSR). Hex heads and wrench flats on a screw-threaded injector tube that the patent's own text says must be "insert[ed] and remove[d]" for cleaning and repair is a pure mechanical expedient, requiring no ingenuity. Allen does not even claim the angular heads as inventive — his specification frames them as access conveniences and reserves his "first to produce" assertion for the 2× placement alone. Cf. Hancock, 98 F. 298 (notches "sliding to place to drop into engagement" were "well enough known"; patent sustained only because of the combination and its surroundings).
• Forward series of holes "of similar capacity" near the smallest diameter, combined area ≤ 1.6× smallest cross-section of the tube: a dimensional/areal optimization of a disclosed structure. In re Aller squarely applies: where the general conditions are disclosed, discovering the optimum or workable ranges by routine experimentation is not inventive. No criticality evidence is offered for the 1.6 figure beyond "not greater than."

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

The motivation is unusually easy to establish, because the references are not merely "analogous" — they are the same art, aimed at the same performance deficiencies, published within a two-decade window in a single small industrial community:

1. Common field and common problem. Every reference is a steam injector/inspirator for boiler feeding, and all of them wrestle with the identical triad Allen names as the "severe conditions of operation": high steam pressure, long lift, and hot feedwater. The 1902 literature is explicit that this is the recognized frontier of the art (injectors "work best with dry steam"; "as the successful operating of the injector is dependent on the feed-water promptly condensing the steam which supplies the power, water of a very high temperature cannot be fed by an injector").
2. The references teach the mechanism Allen relies on. Allen's stated invention rests on a physical fact: a vacuum exists at overflow openings, is stronger the farther the opening is from the throat, and holds an atmospheric check valve closed. Penberthy's automatic overflow and Kneass's vacuum-operated check valve f both teach that an overflow opening draws a vacuum that can actuate a valve. Combining a vacuum-actuated atmospheric valve with a multi-overflow chamber is therefore the predictable use of each element according to its established function — the KSR touchstone.
3. The prior art supplies the express design incentive. Allen admits the prior art already solved the same problem by interposing a check valve between the rear overflow and the forward/intermediate overflows. He frames his contribution as simplification — dispensing with that check valve by rearranging the overflows. But "simplification" of a known mechanism by deleting a part and relocating another is, by definition, a design choice among a finite number of identified, predictable options, and the rearrangement retains the known function (vacuum holding a valve to its seat).
4. Same-community artisans. The Nice patent US662459A (1900) is associated with Wadsworth, Ohio — Allen's own residence (Medina County, Ohio) — indicating a dense, mutually aware population of injector inventors. This rebuts any suggestion that the references were non-analogous or remote.

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5. Bottom line

The strongest combination for a challenger is: US554415A (Penberthy) or US674182A (Sticker) as primary — each disclosing a multi-overflow chamber in an automatic feed injector, in combination with a vacuum-actuated check valve closing an atmospheric overflow port, as shown in the admitted prior art and in the Kneass/Sellers self-acting injector (listed as US376315A) — optionally with the US662459A (Nice) Wadsworth, Ohio, injector as evidence of the level of skill and the proximity of the artisans. That combination defeats claims 1, 3 and 4; claim 2 stands or falls on the unverified question of whether any qualifying reference placed a forward overflow behind the throat.

Confidence and limits. High confidence on the legal framework, the date screening of the reference list, and the qualitative strength of claims 1/3/4. Explicitly uncertain: (i) the actual content of most of the listed references — the page supplies only numbers, dates and titles for US265648A, US304227A, US322342A, US341030A, US349997A, US390031A, US533228A, US557081A, US602537A, US624430A and USRE10811E, and I have not verified their disclosures; assertions about them here are based on title and era, not on inspection; (ii) the mapping of the Peabody-described Kneass structure to US376315A; (iii) the date of US344480; and (iv) the OCR-corrupted text of claim 4. Any of these should be confirmed against the original documents before this analysis is relied upon in a filing or opinion.