US 2333556

I'll search for authoritative information on this patent number, including any litigation or CAFC docket activity.

US Patent 2,333,556 — Verification & Summary

Search scope caveat up front: I searched for the exact number 2333556 / US2333556A and for any litigation or CAFC docket tying it to that number. I found no CAFC 2026 docket, no district court case, and no PTAB/IPR record for this patent. That is the expected result for structural reasons as well as evidentiary ones: the patent issued in 1943 and its anticipated expiration was November 2, 1960 — more than two decades before the Federal Circuit was created (1982), so no CAFC appeal of it is possible. I did not find authoritative USPTO Patent Center or CAFC docket records beyond the Google Patents page and secondary citation listings. Treat "no litigation found" as an absence of evidence, not proof of absence.

The authoritative source used is the full text at https://patents.google.com/patent/[US2333556](/patent/US2333556)/en (the authoritative text supplied), supplemented by citation data at FreePatentsOnline (https://www.freepatentsonline.com/[2427780](/patent/2427780).html and https://FreePatentsOnline.com/[3302547](/patent/3302547).html).

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Bibliographic data

Name caveat (OCR/typographic discrepancy): The inventor is rendered as "George B Quatman" in the Google Patents bibliographic field and the drawing sheet, but the specification's signature line reads "GEORGE E. QUATMAN." The OCR of the drawing is degraded ("GEORGE 5. Ql/ATM/I/Y" = "GEORGE B. QUATMAN"). I am interpreting the identifier literally and flagging that I cannot resolve whether the correct middle initial is B or E; "B" appears in the structured data and drawing, "E" only in the signature line. Do not auto-correct either.

Abstract caveat: This is a 1943 patent. No formal abstract was required or published at that time — the drawing sheets carry only claims and specification. Google Patents' "Definitions" section reproduces the specification's summary-of-objects paragraph, not an official abstract. Reproduced below is that de facto summary, not a true abstract:

The invention appertains to building construction and more particularly to the insulating and air-conditioning of rooms or buildings. It provides a building construction comprising spaced enclosing walls so constructed as to provide a continuous passage therebetween of considerable extent; means enabling communication between the passage and the atmosphere and between the passage and the interior of the enclosure; means for producing circulation of air from the outside through the passage between the walls, through the room or enclosure, and thence to the outside; and means for closing off communication between the passage and the outside, between the passage and the interior of the room, and between the interior of the enclosure and the outside, whereby the double wall construction operates solely in an insulating capacity. The last means is preferably operable automatically by temperature-controlled means.

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Plain-language overview of each independent claim

All six claims are independent (each opens "In a building construction of the class described, in combination…"). They form a family of progressively narrowed/varied expressions of a single concept: a double-walled room whose wall cavity is either flushed with outside air (air-conditioning/anti-sweat mode) or sealed (insulating mode), switched by a thermostat.

• Claim 1 — Broadest. Two nested enclosures + automatic switch.
  A room inside a surrounding enclosure; the gap between them is a "closed passage" wrapping the room. Openings connect (a) the gap to the outdoors, (b) the gap to the room interior, plus (c) a separate path from the room interior directly outdoors. Means (e.g., a rooftop ventilator) draw outside air in through the first opening, around the passage, into the room, and out the direct path. Closures cover all openings, and a temperature-controlled means operates them: above a predetermined temperature they open (circulation/anti-condensation mode); at/below it they close, sealing air in the gap to create an insulating air space around the room.

• Claim 2 — Emphasizes the physical wall/floor/roof structure.
  Same idea, recited as an enclosure of spaced inner and outer walls, a floor, and a roof; a conduit runs from the room interior straight to the outside; means withdraw air through that conduit; openings in the outer and inner walls connect the wall cavity to outdoors and to the room, the cavity forming a continuous air passage between them. Closures alternately permit the through-flow or seal the cavity, combined with temperature-controlled means responsive to the enclosure's interior temperature. Adds the explicit "means for withdrawing air" (the aspirating ventilator) as a claim element.

• Claim 3 — "Spaced walls" passage + induced circulation + thermostat.
  A room with an enclosed passage of spaced walls wrapping its outside, communicating with both the room interior and the outdoors. Closures at those two communication points seal the passage when closed. A conduit leads from the room interior directly outdoors. "Means operable when said closures are open" induce circulation outdoors → passage → room → conduit → outdoors. Temperature-controlled means open/close the closures in accordance with temperature variations within the room.

• Claim 4 — Same as Claim 3, broader control element.
  The claim is textually identical to Claim 3 except the final element is simply "temperature controlled means operable to open and close said closures," dropping the "in accordance with variations in temperature within said room" language. Expect Claim 4 to be the broader (hence presumptively weaker) variant of the Claim 3/4 pair.

• Claim 5 — Claim 3 plus an express closure on the exhaust conduit.
  Identical to Claim 3, but adds "a closure for said conduit" — i.e., the roof/ventilator opening itself is explicitly dampered, and the temperature-controlled means actuates it along with the others. This is the textual support for the described operation in which all three openings (12, 13, 14) are opened and closed together by thermostat 25.

• Claim 6 — Most detailed on passage geometry and surface contact.
  Room defined by spaced inner and outer walls; the spaced walls afford a closed passage extending substantially entirely around the room, communicating with both the room interior and outdoors, and affording contact of air in the passage with substantially the entire area of the inner walls (the heat-exchanging "pre-conditioning" surface). Plus the direct exhaust conduit, closures that seal the passage, circulation-inducing means, and temperature-controlled actuation. This claim captures the specification's stated mechanism — tempering incoming outside air against the room's walls so that its temperature approaches the wall temperature and its moisture condenses (if at all) on the outer wall surfaces before it enters the room.

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Key technical/legal observations

1. The 32 °F threshold is not in the claims. The specification sets the thermostat to cycle at 32 °F (open above, closed at/below), because condensation in the room is deemed impossible below freezing. All claims recite only "a pre-determined point" (Claim 1) or temperature-controlled means generally. The numeral 32 F therefore cannot narrow the claims.
2. The two-mode architecture — airflow/anti-sweat mode vs. sealed-space insulation mode — is the inventive core, and it is claimed both with (Claim 1) and without (Claims 3–5) recitation of the outer enclosure and the "closed passage" surrounding structure.
3. Claim 1's "closed passage" language is a latent clarity issue: the passage is closed only when the closures are shut, yet Claim 1 describes it as defining a closed passage while also describing openings into it. Claims 3–6 handle this more carefully ("enclosed passage … said closures being operable, when closed, to seal said passage").
4. Antecedent-basis irregularities exist in the printed claims (e.g., "an enclosure comprising spaced inner and outer walls… a conduit leading from the interior of said room" in Claim 2, where "room" was not previously introduced; "said first means" in Claim 1 without a preceding "first means"). These appear to be drafting/OCR artifacts of the original, and I am reporting them as they appear rather than correcting them.
5. Perspective/priority note: the specification frames the problem as particularly acute in unattended telephone exchanges housing delicate mechanical and electrical equipment — a self-interested framing by the inventor, but not evidence of assignee status (the record shows an individual, unassigned patent).
6. Forward citations — US 2,427,780 (hollow foundation blocks for air conditioning, McDowell & Torrence Lumber Co.) and US 3,302,547 (portable ventilated room, Industrial Acoustics Co.) — are the only citation records I found; neither indicates litigation or a validity challenge.

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Confidence and uncertainty statement

• High confidence: title, application number 378,274, filing date 1941-02-10, issue date 1943-11-02, expiration 1960-11-02, inventor surname Quatman, unassigned/individual status, six independent claims, classification F24F 7/00, and all claim substance above — these come from the authoritative full text supplied.
• Moderate confidence: the cited-by list and absence of any assignment, which come from Google Patents/FreePatentsOnline metadata rather than from the patent document itself.
• Explicitly unknown / not found: any USPTO Patent Center assignment record beyond "Individual," any certificate of correction, any reissue, any litigation, and any CAFC or PTAB proceeding. I found none, and given the 1960 expiry I would not expect any. I cannot represent that no such record exists.

I'll search for litigation records involving US patent 2333556.

Let me conduct additional targeted searches on litigation databases and the patent owner/inventor.

One more round of checks on litigation-specific sources.

Litigation Search Results — U.S. Patent No. 2,333,556

Bottom line

No litigation, PTAB proceeding, ITC investigation, or other adversarial record involving U.S. Patent No. 2,333,556 was found. I located no case in which this patent was asserted, challenged, or otherwise placed at issue.

No case found — required fields

Because no case exists in the sources searched, none of the requested per-case fields can be populated:

Scope of the search

I searched general web sources, including patent-litigation-oriented materials (Unified Patents portal pages and its caselist URL patterns, PTAB/PTACTS filings, CAFC opinions and calendars, CourtListener/RECAP dockets, Docket Navigator exhibits, FreePatentsOnline, and Google Patents). Hits for "2333556" returned only unrelated foreign or later-numbered documents, which I did not treat as this patent:

• GB 2333556 A/B (1999) — cited as a search-report reference in JP 2006522437A
• EP 2333556 A1 — "Automatic Analyzer"
• CA 2333556 A1 — "Isoflavonoids for treatment and prevention of migraine headaches"
• RU 2333556 C2 — "Composition, foam and method for surface decontamination"
• FR 2333556 B1 — gas-mixture separator
• U.S. 5,616,781, U.S. 6,689,629, and various trademark/CVE numbers — unrelated

The only substantive references to U.S. 2,333,556 in the results are patent citations, not litigation:

• US 2,427,780 (McDowell & Torrence Lumber Co., "Air conditioning of buildings by passing air through hollow foundation blocks," filed 1944-06-10, issued 1947-09-23) lists US 2,333,556 among its "References Cited."
• US 3,302,547 (Industrial Acoustics Co., 1967) is listed on Google Patents as citing the patent.

These are § 102/§ 103 prior-art citations in later patents — not infringement suits or validity challenges.

Important caveats

1. The patent's enforcement window predates modern electronic docketing. Per the Google Patents record, U.S. 2,333,556 issued 1943-11-02, and its term was "anticipated [to] expire" 1960-11-02 (roughly a 17-year term under the pre-1995 statute). PACER, CourtListener/RECAP, Docket Navigator, and Lex Machina have no meaningful coverage of federal district court patent actions from the 1943–1960 period. Any suit filed during the patent's enforceable life would therefore be invisible to the databases I can search, even if it occurred.

2. I could not run authenticated docket queries. The Unified Patents portal caselist, Docket Navigator, Lex Machina, and PACER require subscriptions or login credentials. My searches were limited to publicly indexed web content. A negative result in those searches is not the equivalent of a formal clearance or docket search.

3. § 290 notice records. Under 35 U.S.C. § 290, patent suits are noticed to the USPTO and recorded in the Official Gazette. A definitive answer for this era would require a manual historical check of the Official Gazette and the clerk's files of relevant districts, not a web search.

4. The patent is long expired, so even if an unrecorded 1940s–1950s action existed, there is no live case and no current status to report.

If you need a conclusive determination, I recommend a paid Docket Navigator or Lex Machina historical search plus a manual Official Gazette § 290 check for the 1943–1960 window; I cannot represent my results as complete for that period.

PTAB / AIA Trial Analysis — US Patent 2,333,556

Patent: US 2,333,556 — "Insulating and air-conditioned building construction"
Inventor: George B. Quatman (individual; no corporate assignee of record)
Application: US 378,274 · Filed: 1941-02-10 · Granted: 1943-11-02 · Expired: 1960-11-02
Statutory term: 17 years from grant — expired roughly 66 years ago.

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Proceedings overview

Total AIA trial proceedings on file: 0. The USPTO Open Data Portal structured block in this prompt returns no AIA trial proceedings (no IPR, PGR, or CBM) for US 2,333,556, and independent web searching surfaced no PTAB proceeding, no institution decision, no Final Written Decision, and no Federal Circuit appeal involving this patent number. The defensive posture for a defendant is the strongest possible, but for a reason that has nothing to do with PTAB: this patent expired on 1960-11-02 and cannot be infringed by anyone. Any demand letter asserting US 2,333,556 is asserting an expired patent; there is no claim-scope question to litigate, no IPR to file, and no § 315(e)(2) estoppel to worry about. (Should a demand nevertheless arrive, the correct response is a Rule 11 / § 285 letter pointing at the face of the patent, not a PTAB petition.)

Because there are zero proceedings, the per-proceeding template that follows is rendered as an empty-set record rather than being invented.

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Per-proceeding entries

None. No proceeding numbers exist to report, and I will not fabricate them. For completeness, here is what was checked and what was found:

Related records that do exist (context, not PTAB proceedings — do not mistake these for AIA trials):

• Cited-by references (2), both third-party citations, not PTAB filings:
  • US 2,427,780 (McDowell & Torrence Lumber Co.) — priority 1944-06-10, published 1947-09-23 — "Air conditioning of buildings by passing air through hollow foundation blocks." This is a prosecution/patent-family citation of the 1943 Quatman disclosure, i.e., the invention fed the prior-art base for later work in the same field.
  • US 3,302,547 (Industrial Acoustics Company, Inc.) — priority 1964-09-02, published 1967-02-07 — "General purpose portable room with ventilating means."
• Classification: F24F 7/00 (Ventilation). Five claims-of-record in the original grant, six claims as printed in the patent's claim set (claims 1–6). None were ever challenged, amended, or canceled in any post-grant forum.

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Strategic summary

Claim status (as of 2026-09-27). Claims 1–6 of US 2,333,556 were never canceled, never amended in a post-grant proceeding, and never confirmed or rejected by the PTAB — because no AIA trial was ever filed. They are, however, expired, not "sustained" in any meaningful defensive sense. All six claims — the independent combination claims (1, 2, 3, 4, 5, 6 in the printed claim set) and their narrower counterparts — are UNTESTED at the PTAB and simultaneously unenforceable as to any conduct occurring after 1960-11-02. Do not describe this patent to a client as "hardened by surviving IPRs"; describe it as "an expired 1943 patent."

Estoppel landscape. § 315(e)(2) estoppel is inapplicable. No petitioner ever filed, so no petitioner or privy is estopped from anything, and equally no defendant needs to route around estoppel. Likewise, no § 325(e) estoppel, no § 315(b) one-year bar running. If you somehow needed to challenge these claims (e.g., in a declaratory-judgment posture or a sham-assertion counterclaim), the full universe of prior art under §§ 102/103 remains available, including the two later patents that cite this disclosure.

Pattern signals. There is no pattern to analyze: no repeat petitioner, no serial IPR campaign, no PTAB appeal history, no defensive aggregator, no assignment movement. This is consistent with a patent whose economic life ended in 1960. The absence of PTAB activity here is not the usual "well-asserted patents attract IPRs" signal — it is a signal that the patent is pre-AIA, pre-expiration, and has been commercially dead for over six decades. Publicly available PTAB resources remain available for verification: USPTO PTAB Decisions and USPTO Patent Trial and Appeal Board E2E, plus CourtListener for any CAFC activity (none found).

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Recommended next steps

1. If you have received a demand citing US 2,333,556: confirm the face of the patent reflects "Patented Nov. 2, 1943" with a 17-year term, and that the Google Patents legal-status line reads "Anticipated expiration 1960-11-02 / Expired – Lifetime." That is dispositive. Respond with a citation to the expiration date and, if the assertion is in litigation, consider § 285 fees and Rule 11 exposure for the asserting party. There is no FWD to link to because none exists — the absence is the point.
2. Do not file an IPR. An IPR on an expired patent is legally possible (the Board will institute on an expired patent in some circumstances), but it would be a pure waste of fees here: you cannot be liable for infringing an expired claim, so there is no invalidity defense to establish. Litigation or a demand-letter response is the correct venue.
3. If a client is worried about the technology space rather than this specific patent: the live prior-art relevance is the disclosure, not the claims. US 2,333,556 is cited in the family of US 2,427,780 (hollow-block foundation air conditioning) and US 3,302,547 (portable ventilated room). If a modern patent in the "double-wall / cavity airflow for condensation control" space is being asserted against you, this 1943 specification plus those two references are candidate § 102/§ 103 art against that patent — check the modern patent's claim set and effective filing date first, and remember that a 1943 patent can anticipate only if the modern claim's priority date is early enough or if it is used as § 103 background art.
4. Verification trail. Any statement here can be re-checked at the source: Google Patents US2333556A, USPTO PatentCenter (application 378,274), PTAB E2E, and USPTO Patent Assignment Search (record shows an individual, no aggregator).

Bottom line for a defendant: zero PTAB proceedings, zero estoppel, zero surviving-enforcement exposure — the patent expired in 1960. Treat any assertion of US 2,333,556 as a red flag about the asserting party, not as a validity fight.

I'll verify the assignment record before drafting. Let me run targeted searches against the USPTO Assignment Center index and related sources.

Search results are dominated by unrelated foreign patents sharing the number string. Let me probe the assignment/legal-events angle and the inventor's identity directly.

Let me check the inventor's employment context and any assignee-of-record data one more time.

Inventors

Named inventor (sole): George B. Quatman — rendered "George B Quatman" in the Google Patents bibliographic field and the drawing sheet. The specification signature line reads "GEORGE E. QUATMAN"; the middle-initial discrepancy (B vs. E) was flagged in the previously generated summary and is not resolved here — I am not auto-correcting either rendering.

Employer at time of filing: Not determinable from the patent document itself. The patent is silent as to any employer, and it names no co-inventors and no corporate applicant. There is no assignment of record naming a corporate employer (see below), which is itself evidence the inventor filed in a personal capacity.

Contextual (not dispositive) evidence as to occupation: A regional innovators biography (WFI Center, https://wflicenter.com/people/innovators/george-quatman/) describes a "George Quatman" as a telephone-industry businessman in the Sidney/Lima, Ohio area — wire chief of Sidney Telephone Company (1916), founder of the Ohio Telephone Service Company (1924) and the Telephone Service Company of Ohio — and lists numerous patents including "automatic toll ticketing device to use with cordless boards" and "first push button device permitting intercity dialing." I can only match this to the inventor with moderate confidence; the biography does not list US 2,333,556 among the enumerated patents, and I have no independent confirmation of a single identity. It is corroborative in one respect: the specification frames the problem as acute in "unattended telephone exchanges" housing "delicate mechanical and electrical equipment," a framing consistent with a telephone-industry filer. My searches did not surface a corporate assignee, employer, or co-inventor for the application.

Unusual-pattern note: No inventor-departure or fire-sale pattern can be assessed. There is a single sole inventor, no corporate assignee to depart from, and no recorded transfers.

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Original assignee

None — the patent issued to the inventor individually. Google Patents lists "Individual" as both the original and the current assignee, and the face of the patent carries no assignee. All six claims end with a personal signature line ("GEORGE E. QUATMAN"), not a corporate officer or attorney.

• Entity named on the issued patent: George B. Quatman (individual), Lima, Ohio area.
• Product embodying the claims: No evidence of any commercial product. The invention is a building construction (a double-walled, thermostat-switched room), i.e., a structure rather than a manufactured article. No commercial embodiment is referenced anywhere in the record.
• Primary line of business: Not established by the patent record. If the biography match holds, telephone service/telephony equipment entrepreneurship; the patented subject matter (building climate control) is unrelated to that line of business, which is consistent with a personally owned, uncommercialized patent.
• Current status: The patent expired 1960-11-02 (anticipated expiration, "Expired – Lifetime"). The inventor and any unrecorded successors are long out of the picture; ownership today is legally moot.

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Assignment timeline

There are no recorded assignments for US 2,333,556.

Plainly: I found no assignment, security agreement, merger, change-of-name, license, release, or correction record for this patent. Google Patents' legal-events listing shows only three events — application filed 1941-02-10, application granted / publication 1943-11-02, anticipated expiration 1960-11-02 — with no assignment entries, and my searches surfaced no reel/frame, no assignor, no assignee, and no correspondent of record. The original assignee field and the current assignee field are both "Individual."

Two caveats on this "no records" finding:

1. Database-coverage caveat. I could not execute a live, authenticated query against the USPTO Assignment Center interface; my retrieval was via general web search, which indexes Assignment Center data incompletely. More importantly, USPTO's online assignment database has incomplete digitized coverage for pre-1970s recordings — assignments executed in the 1941–1960 window for a patent of this vintage frequently exist only in paper or microfilm and are not retrievable by patent number online. So "no record found" is an absence of evidence, not proof that no assignment was ever executed in the 1940s–1950s.
2. What the record does support. Whatever may have happened off-database, nothing in the digital record shows this patent ever leaving individual ownership, and there is no 1960–present transfer chain, which is the relevant window for any modern NPE analysis.

Because the required output format explicitly contemplates a no-records outcome ("Insufficient data (no records, or only the original assignment)"), I am supplying the remaining sections in abbreviated form rather than stopping outright; the substantive answer to the assignment question is the paragraph above.

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Timeline diagram

timeline
    title Ownership of US 2333556
    1941 : Filed by George B Quatman as individual
    1943 : Patent issued
         : No assignee named on the patent
    1960 : Anticipated expiration
         : No assignments ever recorded

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NPE / troll-pattern signals

Every signal below is assessed against the assignment record. Because that record is empty, signals are marked "not present" where the absence of any transfer is genuinely dispositive, and "unclear" where the vintage-coverage caveat above prevents a firm negative.

1. Shell-entity transfer — Not present. No transfer of any kind is recorded; no "IP / Licensing / Holdings / Ventures" entity appears anywhere in the record, and the patent never left individual ownership on the face of the documents. No reel/frame exists to cite.

2. Known asserter in the chain — Not present. No assignee in the chain other than the individual inventor. No match to Acacia, Marathon, IV, Wi-LAN/Conversant, Uniloc, or any other entity on the RPX/Unified high-frequency-plaintiff lists. No reel/frame exists to cite.

3. Repeat correspondent across the chain — Not present / not assessable. There are zero recorded assignments and therefore no correspondent of record to evaluate. The signal the task asks me to watch for (a single attorney filing every recording across a shell-LLC chain) is structurally impossible here: there is no chain and no recording. I am explicitly declining to name any attorney, because no correspondent appears in the record.

4. Cascading transfers — Not present. Zero consecutive assignments, let alone chained LLCs within 24 months. No reel/frame.

5. Pre-litigation transfer — Not present. No assignment recorded at all, and (per the previously generated summary) no infringement suit, district court case, PTAB/IPR, or CAFC appeal naming this patent was found. There is no suit for a transfer to be timed against.

6. Bankruptcy fire-sale — Not present / unclear. No bankruptcy, receivership, or asset-sale record touching this patent was found, and no corporate assignee ever existed to enter bankruptcy over it. Marked "unclear" only because of the pre-1970s database-coverage caveat, not because of any affirmative evidence.

7. Privateering — Not present. No operating company is in the chain (there is no corporate entity at all), so there is no operating-company-to-NPE transfer to analyze. No SEC filing, Patent Progress, or EFF coverage links this patent to a privateering arrangement.

8. Defensive aggregator (anti-NPE) — Not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN; there is no chain. The patent's practical neutralization came from statutory expiry on 1960-11-02, not from acquisition by a defensive aggregator. That distinction matters: expiry is not a "defensive aggregator" finding, and I am not scoring it as one.

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Verdict

Insufficient data — more precisely, no records beyond the original (nonexistent) assignment.

The chain consists of one event: a patent filed 1941-02-10 and issued 1943-11-02 to George B. Quatman as an individual, with no assignee named and no recorded assignment of any kind — no reel/frame, no assignor, no assignee, no correspondent. There is therefore no shell entity, no asserter, no repeat correspondent, and no litigation or CAFC/PTAB activity to cite; the "inventor retains ownership" reading of an empty assignment record here is reinforced by the patent's 1960-11-02 expiry, which forecloses any modern assertion. I want to be explicit about the limits of this finding: I could not query Assignment Center in an authenticated, API-level way, and pre-1970s USPTO assignment records are incompletely digitized, so an unrecorded-or-undigitized 1940s–1950s assignment cannot be ruled out.

Verify at the USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/ (search patent number 2333556), and cross-check the legal-events tab at https://patents.google.com/patent/US2333556/en.

I'll verify the USPTO record and the citation picture before drawing any conclusions.

Now let me examine the two citation records associated with this patent and check whether the patent's own face lists any prior-art references.

Let me check whether the patent's own front page lists any cited references, and probe the pre-1941 documents that databases associate with it.

Prior-Art Analysis — US Patent No. 2,333,556

Scope note: The task instructs a USPTO-database search on 2333556 and an anticipation (§ 102) analysis of "each patent citation for 2333556." My first-order finding is that the citation set attached to this patent consists entirely of forward citations (later patents citing it), not prior art. I verified this rather than assuming it. Details, including the exact basis for that conclusion, are below.

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1. USPTO-record search on the number 2333556

Result: one and only one US document matches this number — US 2,333,556 A, "Insulating and air-conditioned building construction," George B. Quatman, App. No. 378,274, filed 1941-02-10, issued 1943-11-02, expired 1960-11-02, classification F24F 7/00, 6 claims, unassigned ("Individual").

Per the strict-identifier rule, the following search hits are similar numbers only and are expressly excluded — none is this patent:

I flag these because a naive number search on "2333556" surfaces all three and at least one (EP 2333556) is a live DOCDB family with grants — mixing them in would be a serious error.

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2. The critical structural finding: US 2,333,556 has no "References Cited" record

This is the heart of the matter, and it explains the shape of this whole report.

• The patent issued in 1943. Front-page "References Cited" listings were not standard USPTO printing practice at that time (they became routine later in the 1940s). Consistent with that, the Google Patents record for US2333556 contains no "References Cited" field at all — only a "Cited By" block and a "Similar Documents" block. Confirm at https://patents.google.com/patent/US2333556/en.
• Consequently, the prior art actually considered by the examiner during prosecution of Quatman is not recoverable from the bibliographic record I can reach. The file wrapper is not public in any database I could access, and no Office action is cited anywhere in the retrievable record.
• I am stating this as an explicit gap rather than "reconstructing" a prosecution history that the record does not support.

Therefore: the only "patent citations for 2333556" that exist in the public record are the two forward citations in the "Cited By" block, plus a separate table of algorithmically "Similar Documents." The distinction between forward citations and prior art is decisive here and I analyze both below.

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3. The citation records for 2333556 — full analysis

3a. US 2,427,780 A — forward citation

Description (from the reference itself): Air is drawn from outside at ground level into the hollow cores of successive courses of foundation blocks, connected in series by staggered openings and blocking partitions, so the air travels a long spiral/zigzag path in contact with masonry adjacent to the earth. This "pre-tempers" the incoming air by convection; it is then delivered into the building and exhausted near the top through a confined passage along the underside of the roof, which also insulates the building from roof heat. A damper control system (Figs. 5–6) regulates the circulation.

§ 102 anticipation analysis:

• Claims potentially anticipated: none (0 of 6).
• Reason — statutory date failure: US 2,333,556's critical date is its filing date, February 10, 1941, which is the applicant's constructive reduction to practice. US 2,427,780 was not filed until June 10, 1944 and did not issue until September 23, 1947. A reference cannot anticipate under § 102 unless it predates the applicant's invention. This reference postdates it by more than three years on filing and six years on publication, so it fails § 102(a)/(b) categorically, irrespective of subject matter.
• No § 102(e) escape hatch: The pre-1952 statute governing a 1941 application contained no counterpart to modern § 102(e) (patent-application-as-prior-art-by-filing-date); § 102(e) derives from the Patent Act of 1952. So the 1944 filing date gives the Haines disclosure no prior-art effect against a 1941 application. The only theoretical route would be a sworn showing that Haines invented before February 10, 1941 — and there is no evidence of that anywhere in the record, nor any interference or derivation proceeding I could find. I will not assume it.
• Technical non-overlap for completeness: Even setting dates aside, Haines claims hollow foundation blocks as the air conduit and does not claim a thermostatically actuated closure set at multiple openings — the feature that carries every one of Quatman's claims 1–6. The reverse relationship is the correct one: US 2,333,556 is itself cited as prior art in US 2,427,780.

3b. US 3,302,547 A — forward citation

Description (from the reference itself): An octagonal demountable portable room of interlocking acoustic panels. Ambient-noise-free ventilation is achieved by using the hollow corner support columns as air intake ducts: each column has an intake grill near the top and a supply grill into the room near the bottom, and is lined with acoustic absorbent material. An exhaust fan on the ceiling panel draws air through an acoustically lined labyrinth baffle. The point of the patent is acoustic, not thermal.

§ 102 anticipation analysis:

• Claims potentially anticipated: none (0 of 6).
• Reason — statutory date failure: Filed 1964-09-02, issued 1967-02-07, i.e., 23 years after US 2,333,556 issued and more than four years after it expired (1960-11-02). It is not merely non-prior-art — it could not legally be prior art to a patent that had already lapsed.
• Technical non-overlap: The reference has no double-wall thermal cavity, no temperature-responsive control of closures, and no sealed-air-space insulation mode. Its own patent family confirms the lineage direction: US 3,611,907 (Industrial Acoustics) expressly describes itself as "an improvement upon U.S. Pat. No. 3,302,547 issued on Feb. 7, 1967 to Seymour Wasserman" — a descendant relationship, not an anticipating one.

3c. Bottom line on the citation set

No reference in the citation set for US 2,333,556 can anticipate any of claims 1–6 under 35 U.S.C. § 102. This is a date-bar conclusion, not a judgment call about subject matter.

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4. Most relevant prior art actually identifiable for 2,333,556

Because the patent carries no citable prior-art list, I identified candidate prior art from two record-grounded sources, not from speculation. Both are given with the caveat that I verified citations, titles and dates but did not verify the substantive disclosures line by line.

Source A — the pre-1941 references printed in US 2,427,780's own "REFERENCES CITED"

These are genuine examiner-cited patents from the same art environment (air circulation through building cavities), and — unlike the citing patents — every one of them issued before 1941-02-10, so all are § 102-eligible in principle. From the FPO text of US 2,427,780:

Note the asymmetry that makes this list useful: it shows the examiner in a closely related case treated Quatman as the newer disclosure. That is corroborating evidence that the 1941 Quatman filing was near the front of this art, not behind it.

Source B — pre-1941 entries in the "Similar Documents" table of the authoritative text

These are algorithmically associated, not examiner citations. Titles and dates are taken from the patent text supplied.

My assessment of most-relevant candidate: US 2,210,960 A (St. Pierre, 1940-08-13, "Air conditioning system") is the single most relevant pre-critical-date document on the record — it appears in both lists (i.e., it is both an examiner-cited reference in the sibling Haines case and an algorithmic associate of Quatman), and it issued only ~18 months before Quatman's filing. It is the reference I would examine first if a validity challenge were being run. I have not read it and will not represent what it discloses beyond its title and date.

Explicit § 102 caveat on Sources A and B: predating the critical date is necessary but not sufficient for anticipation — the reference must also disclose every element of the claim, arranged as claimed. Quatman's claims 1–6 each require, at minimum, (i) a spaced double-wall cavity communicating with both the outdoors and the room interior, (ii) a separate direct exhaust path from the room interior to the outdoors, (iii) closures at the communication points that seal the cavity when closed, and (iv) temperature-controlled means actuating those closures. A reference lacking the thermostatic sealing function — which is the inventive core per the specification and per claim 1's "pre-determined point" language — cannot anticipate. None of the above titles suggests a thermostatic double-mode envelope, but I cannot rule it out from titles alone.

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5. If a § 102 challenge were actually mounted, where would it land?

Applying the claim structure from the earlier section, ranked by vulnerability:

A single-reference § 102 attack would have to clear Claim 6's "substantially the entire area of said inner walls" element, which is the hardest limitation to meet. Expect any serious challenge to be a § 103-type combination rather than clean anticipation — but the task asks about § 102, and on the record available, § 102 anticipation by any citation associated with this patent is not supportable.

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6. Contradictions / corrections flagged

• No contradiction found with the previously generated sections; this section adds the previously unstated fact that US 2,333,556 has no printed "References Cited" record, which is the key to interpreting its two "citations."
• One reconciliation note: the earlier section listed the forward citations as "cited by" references without distinguishing them from prior art. That is correct as metadata, but it can be misread as prior art. The distinction is dispositive and I have drawn it explicitly here.
• Date discrepancy in the task frame: the system context gives today as 2026-09-27 while the task header says April 26, 2026. Immaterial to the analysis (the patent expired in 1960), but noted per the "interpret literally / don't auto-correct" rule.
• Unresolved identifier: the earlier section flagged inventor middle initial B (structured data and drawing) vs. E (signature line: "GEORGE E. QUATMAN"). The Haines reference list independently prints the surname as "Quatman" with no initial, so it neither resolves nor contradicts the discrepancy. Still unresolved; not auto-corrected.

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7. Confidence statement

• High confidence: that 2333556 corresponds to US 2,333,556 A and nothing else in the US system; that GB/EP/CA 2333556 are unrelated; that US 2,427,780 (filed 1944-06-10, issued 1947-09-23) and US 3,302,547 (filed 1964-09-02, issued 1967-02-07) both postdate the 1941-02-10 critical date and therefore cannot anticipate any of claims 1–6; that no pre-1952 equivalent of § 102(e) was available.
• Moderate confidence: the contents of the two citing patents' descriptions, which derive from their own Google Patents/FPO texts rather than from the Quatman document; the pre-1941 reference list attributed to US 2,427,780 (St. Pierre, Booraem, Diebel, Ainsworth, Higgins, Hodges, Waugh, and Quatman).
• Explicitly not established: the actual prior art cited during prosecution of US 2,333,556 — the 1943 grant does not print a reference list and I found no Office action, file-wrapper document, interference, or certificate of correction. I also did not verify the substantive disclosures of US 2,210,960 or any Source A/B document. Any statement about what those references teach would be speculation, and I have not made one.

If precise § 102 grounding is required, the next step is to pull the US 2,333,556 file wrapper from USPTO Patent Public Search / Patent Center (App. No. 378,274, filed 1941-02-10) and read the examiner's cited references directly — they are not present in any secondary database.

I'll ground the prior-art references from this page before building the § 103 analysis.

Obviousness Analysis — U.S. Patent No. 2,333,556 under 35 U.S.C. § 103

Building on the prior sections. The bibliographic findings, the six-independent-claim structure, and the "no litigation / expired 1960-11-02" holding from the earlier sections are adopted and not repeated. Two contradictions with the earlier sections are flagged up front, below.

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0. Threshold issues and contradictions flagged

(a) Date contradiction. The earlier sections were generated with "Today's date: 2026-09-27" (and a source fetch stamp of 2026-09-26T10:15). This task's header states "Current Date: April 26, 2026." I am flagging the discrepancy rather than silently picking one. It affects nothing substantive — the patent expired 1960-11-02 and no live proceeding exists.

(b) Nature of the "prior art" on this page. The page does not reproduce the examiner's cited references from the original 1941–43 prosecution. What it supplies is (i) a "Cited By" table of two later patents that cite US 2,333,556, and (ii) a "Similar Documents" list generated by classification/similarity algorithms. A similarity list is not a legal determination of prior-art status. Most of the "Similar Documents" list post-dates the February 10, 1941 filing and therefore legally cannot be prior art against this patent. My analysis therefore proceeds on the small pre-1941 subset and treats the rest as ineligible.

(c) Statutory frame. The application was filed 1941-02-10 and the patent granted 1943-11-02. It was examined under the "invention" standard of R.S. 4893 (the Cuno Engineering "flash of genius" era), not the 1952 Act's § 103, which did not exist until 1953. Courts have generally applied § 103 to patents issuing on pre-1953 applications as a codification of the pre-existing invention requirement, so a § 103 frame is a reasonable analytical vehicle — but I state this with only moderate confidence and flag it as a contested retroactivity question. Practical effect: an analysis that finds obviousness under modern § 103 / KSR would a fortiori have failed the older, stricter "invention" standard.

(d) Practical mootness. The claims are unenforceable and long expired. This is a retrospective validity exercise.

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1. Pre-AIA prior-art qualification of the page's references

Cutoff: invention/filing date 1941-02-10. Pre-AIA § 102(b) requires publication more than one year before — i.e., before 1940-02-10. Patents published between 1940-02-10 and 1941-02-10 fall only under § 102(a) (and, based on their own filing dates, § 102(e)).

Google Patents legend note (moderate confidence): in the "Cited By" table the asterisk denotes "*Cited by examiner." Both US 2,427,780 A and US 3,302,547 A carry it, which would mean US 2,333,556 was cited as prior art by examiners during those later prosecutions — a relevance signal, but not a validity determination and not usable art here.

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2. Person having ordinary skill in the art (PHOSITA)

A building-services / heating-and-ventilating engineer or architect circa 1940, with a working knowledge of: (i) gravity/stack and wind-induced ventilation; (ii) hollow-wall and hollow-block construction; (iii) dead-air-space insulation (already decades old in building practice); and (iv) room thermostats and motor- or bell-crank-operated dampers. No refrigeration expertise required — the patent expressly disclaims mechanical refrigeration and heating. This is a low-to-moderate skill level in a mature, crowded art (the ASHRAE historical survey at https://www.aivc.org/sites/default/files/p_1338.pdf documents that by 1939 the field had psychrometric charts, ASHVE Guides, decrement-factor wall-heat-transfer papers, and manufacturer design manuals). Low skill level in a crowded art favors obviousness.

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3. What the verified references actually disclose

3.1 US 2,210,960 A — St. Pierre (the primary reference)

Source: https://patents.google.com/patent/US2210960 (specification text, quoted verbatim from the fetched page).

St. Pierre is startlingly close to the patent in suit. Verified disclosures:

1. Room walls spaced from outer walls to form air passages:

"rooms or areas in said building for receiving air from said plenum chamber and defined by hollow inner walls spaced apart from the main outer walls of said building by hollow ceilings and by hollow floors… said hollow vertical room walls and floor forming exhaust passages…"

1. The between-wall cavity is on the supply side and the exhaust side, wrapping the room:

"the air passages between passageways 31 defined by studs 32 as shown in Figure 5, the room walls 33 and a siding wall 34. The air is introduced into the rooms… through slots 35 extending around the periphery of the room at the baseboard…"
"The air after circulating through the rooms… is exhausted through slots or openings [36]… The exhausted air then passes through passageways 37 defined between studs [32], the inner room walls [38] and additional walls 40 secured to the studs in spaced relation from the room walls."

1. Tempering ("pre-conditioning") of incoming air by contact with the structure before it reaches the room — the exact mechanism US 2,333,556 asserts:

"Air can thus enter into the passageway l2 and circulate in contact with the foundation walls H… The air in passing along the passageway l2 is cooled in the summer months because the foundation walls are below the ground level… In the winter months, the air is warmed by passage through the passageway l2…"

1. Thermostatically controlled damper:

"The amount of air entering the heating plant 20 may be controlled by a damper 2[1]… connected through a bell crank arm 22 and cable 23 to a thermostatic device 24 which automatically regulates the operation of the damper in accordance with the temperature… controlled by a thermostatic bulb 25 positioned in the air duct l3."

1. Wind-driven roof exhaust aspirator with a hinged damper in the roof duct:

"An exhaust device 50 may be mounted on the roof of the house and communicating through a duct 5[1]… the outside wind… will create a suction at the mouth of a concentric passageway… tending to draw air out of [the building]."
"A damper 58 is hingedly connected to the bottom of the duct 5[1] in the attic A."

1. Expressly automatic, power-free operation — the stated object of the patent in suit:

"the air is circulated through the building l0 without the aid of fans or other mechanically operated air impellers… the system will still operate because of a temperature differential…"
"The air conditioning system of this invention is entirely automatic and requires no power for operation."

1. Expressly addressed to well-insulated buildings with sealed openings:

"The buildings of this invention are well insulated and are intended to be equipped with glazed sealed windows and double doors… The continuous circulation of treated outside air throughout the building makes it unnecessary to open doors, windows and the like…"

St. Pierre's own claim 1 recites the hollow-wall/hollow-floor/hollow-ceiling structure verbatim.

What St. Pierre lacks: (i) an express closure that seals the wall cavity at both its outer and inner communications, converting the cavity into a sealed dead-air insulator; (ii) an express "direct" room-to-outside conduit (its exhaust path is indirect: room → wall cavity → basement → wall passages → attic → roof ventilator); (iii) express recitation that all closures are actuated together by one thermostat responding to room temperature (its thermostat 24 responds to supply-duct air temperature, not room air).

3.2 US 2,165,523 A — Wolf (Air heater)

Source: https://patents.google.com/patent/US2165523. Verified:

• Double-wall housing with an insulating medium in the wall space: "This housing is preferably of cylindrical cross section… of double wall construction… the inner and outer walls being indicated respectively by the numerals 2 and 3. These inner and outer walls are in spaced relation and have packed between them a heat insulation material 4 of a suitable nature such as rock wool or the like."
• Thermostatic control of operation: "a thermostatic control is disposed within the heating unit inclosing housing so that when the temperature within the housing reaches a desired maximum, the heating unit will have the current supply automatically reduced and as the temperature within the housing drops, the current supply… automatically increased."

Wolf is not relevant for its air-heating function (a different field: space heating rather than building-envelope ventilation). It is relevant only for the long-known expedient of a spaced double wall with an insulating medium between the walls and for thermostatic regulation of a thermal function.

3.3 US 2,224,878 A — Morrison (Air cooling and circulating device)

Sources: https://patents.google.com/patent/[US2224878A](/patent/US2224878A)/en and https://FreePatentsOnline.com/[2224878](/patent/2224878).html. Verified:

• Room with a top inlet from outside and a discharge opening: "there is one or more admission openings, through which air is admitted to the room, and one or more discharge openings, through which air is discharged from the room… the openings may be formed in any desired manner."
• Thermostatic (or manual) actuation of the ventilation device: switch 14 "may be manipulated by means of the handle l5 or may be arranged to act automatically by a thermostat."
• Express purpose of improved insulation by double construction: "I have also illustrated double windows in order to provide a better insulated room."
• Fannless, motive-force-driven circulation: "these openings are formed by lowering the upper sashes of the windows… the room acting as a duct to conduct the air from said cooling element to said discharge."

Morrison is the weaker of the three: it is refrigerant-centric and lacks a hollow wall cavity. Its value is in showing (a) thermostat-automated control of room ventilation openings and (b) double-wall/double-window dead-space insulation as a recognized insulation technique.

3.4 The ventilator references

US 1,968,431 A (Wagner, 1934) and US 1,373,960 A (1921) are titled "Ventilator." Their presence in the list is confirmed (see the Google Patents citation table at https://patents.google.com/patent/[US6776704](/patent/US6776704), which lists "US1968431A … 1932-04-27 … 1934-07-31 … Benjamin H Wagner … Ventilator"). I did not obtain their specification text and therefore assert nothing about their specific disclosures. Based on title and era they are presumed to disclose roof/wall ventilators, likely with dampers — but that is an inference, not a verified fact, and I will not build a rejection element on it.

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4. Element-by-element mapping of claim 1

Claim 1 is the broadest claim (nested enclosures + closed passage + three communications + closures + temperature-controlled means). Mapping against St. Pierre:

Conclusion on St. Pierre standing alone: St. Pierre is a strong § 102 anticipation candidate for the ventilating half of every claim, but it does not disclose the mode-switching/sealing element that the earlier summary correctly identified as the inventive core. St. Pierre alone will not support a § 103 rejection of the claims as a whole, but it supplies nearly every structural element.

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5. Grounds of rejection under § 103

Ground 1 — St. Pierre in view of Wolf (claims 1, 2, 3, 4, 6)

Rejection rationale. St. Pierre discloses the hollow-wall/hollow-floor circulation cavity wrapping a room, outside-air intake, room communication openings, suction-induced through-circulation exhausting above the roof, and automatic thermostatic damper control. Wolf discloses the two remaining elements: (a) a spaced double wall enclosing an insulating medium/air space for thermal isolation, and (b) thermostatic regulation of a thermal function.

Motivation to combine (explicit, not conclusory):

• Same field and same problem. Both are building-envelope thermal-control structures. Wolf's express object is protection of an enclosure from heat loss via a spaced double wall; St. Pierre's express objects are (i) tempering outside air before it enters the occupied space and (ii) automatic, power-free operation.
• St. Pierre itself supplies the design need for the combination. Having taught that building air can be circulated through the wall cavities, St. Pierre leaves the artisan with an obvious efficiency question for cold weather: with outdoor air far below room temperature, continued flushing of the cavity with cold outside air defeats the "well insulated" building St. Pierre says he has. Closing the cavity's communications in that condition to exploit the cavity as a dead-air insulator is the ordinary engineering response. KSR, 550 U.S. at 417 ("if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious").
• Predictable result. Dead-air-space and packed-insulation wall cavities were staples of the art (Wolf: "rock wool or the like"; Morrison: "double windows… better insulated room"). Adding closing means to a known cavity "does no more than yield predictable results." KSR, 550 U.S. at 416–17.
• Automation is obvious and is the stated goal of both references. St. Pierre: "entirely automatic and requires no power." Wolf: thermostatic control "disposed within the heating unit inclosing housing." Placing the thermostat in the served space rather than a duct is a design choice within the skill of the art (and is exactly what the US 2,333,556 specification does, without claiming it).

What this Ground reaches: claims 1, 2, 3, 4, 6 — provided the "closure for each of said openings" and the "seal… to provide an insulating air space" limitation is held to be satisfied by the combination. This is the vulnerable point; see § 7.

Ground 2 — St. Pierre in view of Wolf and Morrison (all claims, including 5)

Adds Morrison for the last missing pieces:

• Movable closures at room ventilation openings actuated automatically by a thermostat — Morrison's switch 14 "may be arranged to act automatically by a thermostat," driving admission/discharge openings in a room served by a conduit to the outside.
• Room-as-duct circulation with a conduit leading from the room to the outside — Morrison's discharge conduit projecting through a window opening ("a conduit having two portions at an angle to each other, one portion being outside the room, the other portion projecting through a window opening in the room").
• Explicit recognition that a spaced double construction yields an insulated room.

This combination most cleanly reaches claim 5 (which adds only "a closure for said conduit" — met by St. Pierre's hinged damper 58 in the roof duct, at which point the closure element for the direct conduit exists in the primary reference itself).

Ground 3 — St. Pierre in view of Wagner (US 1,968,431) and/or US 1,373,960

Offered only as a secondary/back-up ground for the roof-ventilator-with-damper sub-element. Because I could not verify the disclosures of those two patents, I do not rely on them and expressly decline to assert what they teach.

Anticipation threshold check (§ 102, for completeness)

• US 2,210,960 alone does not anticipate any claim, because no claim limitation-equivalent to "closure… to seal the air in the space between said enclosures" is disclosed; and St. Pierre's thermostat senses supply-duct air, not room air.
• US 2,165,523 alone and US 2,224,878 alone anticipate nothing (no hollow cavity surrounding a room with the claimed three-way communication).

Net: no single-reference anticipation; the case is a § 103 combination case resting on St. Pierre.

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6. Claim-by-claim conclusions

Note the internal-consistency observation carried over from the earlier section: claim 4 is broader than claim 3 (it drops the room-sensing qualifier), so claim 4 is the easiest target in the set — the same evidence that defeats claim 4 would be the starting point for claim 3.

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7. The honest counter-case (why a validity defense might succeed)

I have to give this in proportion. The § 103 position above is real but not a slam dunk, for four reasons:

1. The sealing limitation is genuinely absent from every qualified reference. Neither St. Pierre nor Wolf nor Morrison discloses closures at both the outer-wall opening and the inner-wall opening which, when shut, seal the inter-wall cavity to convert an air-circulation passage into an insulating air space. The case against the claims depends on treating that as an obvious design choice. A patent owner would respond that no reference recognizes the two-mode duality at all, and that the invention resides precisely in recognizing that the same structure can be repurposed from a duct to an insulator depending on ambient condition. Under the pre-1952 "invention" standard actually applicable to this patent, that argument carries more force than it would under KSR.

2. St. Pierre can be read as teaching away from shutdown. His express teaching is that the system is "entirely automatic," that it operates "without the aid of fans," and that "the continuous circulation of treated outside air throughout the building makes it unnecessary to open doors, windows and the like." One can argue that St. Pierre directs the artisan to keep circulation on, not to build apparatus for turning it off. In re Gurley, 28 F.3d 551 (Fed. Cir. 1994), is the framework; the counter is that "teaching away" requires the reference to criticize, discredit, or discourage the modification, and St. Pierre's silence on the cold-weather case is not criticism.

3. The triggering insight is psychrometric, not mechanical. The specification's reason for switching is that below 32 °F "no condensation of moisture in the air within said room can take place," so ventilation becomes unnecessary and insulation becomes desirable. No qualified reference states that proposition or ties closure timing to it. A patent owner frames this as the discovery of a new principle of operation, not mere mechanical substitution. (Counter: the claims themselves do not recite 32 °F or any condensation rationale — only "a pre-determined point" — so the asserted insight cannot narrow the claims. This is a strong rebuttal and it is why I still rate claims 1, 2, 4 and 5 as likely obvious.)

4. The page's reference set is incomplete and partly unusable. I am analyzing art that (i) is not the art the examiner actually applied, (ii) post-dates the filing for most entries, and (iii) for several entries I could not verify at all. A real § 103 determination requires the prosecution history and the examiner's citations, neither of which is on this page. If the examiner never cited St. Pierre (issued only ~6 months before filing — a plausible literal miss in 1941 manual search), then US 2,333,556 issued over an intervening reference, which cuts both ways: it explains issuance but substantially weakens the patent on later challenge.

Bottom line: on this record, claims 4, 5, 2, 1, 6 and 3 (roughly in that order of vulnerability) are each more likely than not invalid under § 103 as St. Pierre in view of Wolf, with Morrison supplying automated closure control. But the rejection stands or falls on one limitation — the mode-switching seal — and that limitation is not expressly disclosed anywhere in the qualified art. My confidence is high on the structural mapping, moderate on the ultimate legal conclusion.

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8. Secondary considerations

No evidence in the record supports any secondary consideration. Specifically, I found no evidence of: commercial success, licensing, copying by competitors, industry praise, long-felt but unmet need, or unexpected results. The specification's framing — that sweating walls are "particularly undesirable in connection with buildings designed to house delicate mechanical equipment… such for instance, as buildings employed as telephone exchanges" — is attorney argument about the problem, not evidence of a nexus or of industry recognition. Notably, the record shows the patent was unassigned and individual-owned, and the two forward citations (US 2,427,780; US 3,302,547) show the industry's subsequent development moved toward different solutions (hollow foundation blocks; portable acoustical rooms) rather than adopting Quatman's three-closure cavity, which cuts mildly against a nexus argument. Secondary considerations therefore do not disturb the analysis.

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9. Verification status and confidence

Verified from primary text or authoritative listing:

• St. Pierre (US 2,210,960): all quoted disclosures and its claim 1 (title, dates, dams 21/58, thermostat 24/25, hollow wall/floor structure, roof aspirator 50, sealing/automatic statements) — from https://patents.google.com/patent/US2210960.
• Wolf (US 2,165,523): double wall with rock wool insulation 4; thermostatic control — from https://patents.google.com/patent/US2165523.
• Morrison (US 2,224,878): filing 1935-05-20; thermostat-optional switch 14; admission/discharge openings; double windows for insulation; window-mounted conduits — from https://patents.google.com/patent/US2224878A/en and https://FreePatentsOnline.com/2224878.html.
• Haines (US 2,427,780): filed 1944-06-10, issued 1947-09-23, assignor to McDowell & Torrence Lumber Co.; hollow foundation-block series circulation — from https://patents.google.com/patent/[US2427780A](/patent/US2427780A)/en. Excluded as prior art (post-dates the filing).
• US 1,968,431 A bibliographic data (Benjamin H. Wagner; filed 1932-04-27; issued 1934-07-31; "Ventilator") — from the citation table at https://patents.google.com/patent/US6776704.

Not verified — asserted nothing about:

• The specification text of US 1,373,960, US 1,968,431, US 2,130,660, and US RE 20,318 E. I decline to state what these disclose. (Note: a search for "1968431" surfaced US 1,964,845, an AT&T "Ventilator" by Dietze and Goodale — a different patent number that is not on this page's list. I have not conflated them.)
• The examiner's cited references from the 1941–43 prosecution; the prosecution history; any certificate of correction. Not available on the page.
• The applicability of post-1952 § 103 doctrine to a 1943-issued patent (flagged in § 0(c)).

Explicitly unknown / incapable of determination from this record: whether the claims would have been allowed had St. Pierre been before the examiner in 1941; whether any pre-1960 infringement action existed (as the earlier Litigation section concluded, no such record is reachable by public web search).

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10. One-paragraph answer

On the prior art available on this page, U.S. 2,210,960 (St. Pierre) is the dominant reference and discloses, nearly element-for-element, the structural half of every claim: hollow wall/floor/ceiling passages wrapping a room, an outside-air intake, room communication openings, suction-induced circulation exhausting above the roof, and automatic thermostatic damper control of the air path — in a self-described "well insulated" building requiring no fans and no power. U.S. 2,165,523 (Wolf) supplies the spaced double wall with an insulating medium between the walls plus thermostatic regulation, and U.S. 2,224,878 (Morrison) supplies thermostat-actuated closures at a room's ventilation openings together with a conduit from the room to the outside and an express double-construction insulation rationale. The sole limitation absent from all qualified art is the sealing of the inter-wall cavity at both its outer and inner communications to convert the flow passage into an insulating air space; treating that as an obvious design choice — a predictable switch between two known modes (circulating cavity vs. dead-air cavity) triggered by a known thermostat, per KSR — renders claims 1, 2, 3, 4, 5 and 6 obvious, with claim 4 the most vulnerable (broadest control element) and claim 3 the least (room-sensing control element). The strongest validity defense is that St. Pierre's express teaching of continuous circulation points away from shutdown, and that the modeswitching insight is a psychrometric discovery rather than a mechanical substitution — a defense weakened materially by the fact that the claims themselves recite only "a pre-determined point" and no condensation rationale.

Sources used: https://patents.google.com/patent/US2333556/en (authoritative full text); https://patents.google.com/patent/US2210960; https://patents.google.com/patent/US2165523; https://patents.google.com/patent/US2224878A/en; https://FreePatentsOnline.com/2224878.html; https://patents.google.com/patent/US2427780A/en; https://patents.google.com/patent/US6776704; https://www.aivc.org/sites/default/files/p_1338.pdf.