US 1713721

I'll run targeted searches for this patent number.

Let me search Google Patents and check litigation/docket sources directly.

Summary: US Patent 1,713,721 ("1713721")

Source used: The authoritative full text of US1713721A was supplied in the user message (Google Patents, fetched 2026-09-29). My independent web searches did not surface a separate USPTO or CAFC record for this number, so the summary below rests primarily on that authoritative text, with the search caveats noted at the end.

Bibliographic data

Abstract

This is a pre-1930 US patent and has no formal abstract. The specification's opening statement of invention serves that role: the invention "relates to a ground-terminal especially designed for use in connection with radio receiving sets, and aims to provide novel means whereby a more perfect grounding will be insured by maintaining the soil in which the ground-terminal is driven, in a moistened condition."

Overview of the disclosure

The device is a driven earth electrode (a "radio ground") that keeps surrounding soil moist to lower ground resistance for a radio receiver:

• A pipe section (5) with a tapered/pointed lower extremity (6) having a discharge opening (7) so water can seep into the soil.
• The pipe's threaded upper end mates with a tubular bushing (8) at the lower end of a funnel-shaped water chamber (9), making the chamber removable for shipping.
• Inside the funnel chamber, crossbars (10) support a filtering material (20) — sand or gravel — so water seeps gradually into the pipe (Fig. 1 embodiment).
• A removable cover (11) prevents evaporation and entry of foreign matter.
• A bolt (12) with nut (13) through the chamber wall provides the terminal for the receiver's ground wire.
• Fig. 3 embodiment: the funnel chamber (9) carries a valve member (16) with a tapered valve (18, tapered extremity 17) and a handle (19) at its top, allowing the user to regulate water flow into the pipe; the bushing threads cooperate with the valve member's extension (15).

Independent claims (plain language)

The OCR of the claims section is partially garbled, so the following paraphrase is careful but not verbatim in places. All claims appear to be independent (none references another claim by number). There appear to be four claims, with the claim 3/4 boundary obscured by a text break in the source ("...means within the [pipe sec]tion, a receptacle at the top...").

1. Ground terminal with moistening supply (claim 1). A ground terminal comprising: a pipe section; a water chamber mounted on the pipe's upper end to feed water into it; an opening in the pipe letting water pass into the surrounding soil; a flow regulator controlling water from chamber to pipe; and a means on the chamber (the bolt/nut) for attaching a wire.
2. Tapered pipe with gradual feed (claim 2). A ground terminal comprising: a pipe section with a tapered extremity having a discharge opening; a water chamber at the pipe's upper end that feeds water gradually to the pipe; and means for restricting water passage from chamber to pipe.
3. Threaded, removable assembly (claim 3). A ground terminal comprising: a pipe section with a threaded upper end and an apertured tapered lower end; a water chamber removably supported on the threaded upper end; means on the chamber to attach a ground wire; and means within the [pipe section/fitting] — the sentence is truncated in the source.
4. Receptacle with filtering material (claim 4, as reconstructed). A ground terminal comprising: the pipe section [with discharge opening]; a receptacle at the top of the pipe for holding water; a filtering material within the receptacle (the sand/gravel 20) regulating the passage of water out of it; and means on the receptacle to attach a ground wire.

Signed by Karl L. Stahl; the specification ends with the conventional "In testimony that I claim the foregoing as my own..."

Litigation / CAFC check (2026)

• I found no Court of Appeals for the Federal Circuit docket entry, appeal, or litigation referencing US 1,713,721 in 2026 or any other year. Given the recorded expiration on May 21, 1946, there is no plausible basis for live 2026 patent litigation; the patent has been in the public domain for roughly 80 years.
• A search for the bare number "1713721" returns several unrelated items — e.g., a Brazilian Superior Tribunal de Justiça proceeding numbered "1713721" (AGRAVO EM RECURSO ESPECIAL 2020/0139592-0) and a CN publication number "1713721" cited in a modern US patent. These are different identifiers from different systems and have no connection to US 1,713,721.

Uncertainty / caveats

• No independent USPTO or Google Patents page was retrieved by my searches for this specific number; I relied on the authoritative full text you supplied. Where my search results (which surfaced unrelated ground-system patents such as US 2,522,879 and US 1,890,737) conflicted with nothing in the supplied text, I treated the supplied text as controlling.
• Claim count and claim 3/4 wording are uncertain due to OCR corruption in the source (e.g., duplicated "1." markers and a mid-word break in claim 3's text). The claim titles above are my plain-language paraphrase, not verbatim quotations.
• The general searches returned zero results for "1713721" + patent litigation/defendant, so I cannot confirm any litigation history beyond the recorded "Expired – Lifetime" status.

I'll search litigation databases for this specific patent number.

Let me try more targeted litigation-specific searches.

Litigation Search Results: US Patent No. 171,3721

Conclusion: No litigation known. I found no record of any lawsuit involving US patent 1713721.

What I searched and what came back

I ran searches across general web indexes and litigation-oriented queries targeting Unified Patents' litigation portal, CourtListener/RECAP, and Federal Circuit materials, using the exact identifiers "1713721," "US1713721," "US 1,713,721," and "1,713,721" paired with litigation terms and with the inventor name and title ("Karl L. Stahl," "Radio ground"). No docket entry, complaint, case caption, or court opinion referencing this patent was returned.

Relevant non-matches (returned by the ID, not the patent)

For transparency, the searches did surface two hits containing the string "1713721." Neither is this patent:

I did note a Federal Circuit brief involving patent 6,218,930 (Network-1 Technologies v. Hewlett-Packard), but that is a different patent number and is not relevant.

Why no litigation is expected — and the limits of my search

The bibliographic record for US1713721 (Google Patents, https://patents.google.com/patent/US1713721/en) explains the null result:

• Filing date: 1928-06-16 (App. No. US285973A)
• Grant/publication date: 1929-05-21
• Anticipated expiration: 1946-05-21 (17-year term from grant) — legal status "Expired – Lifetime"
• Inventor: Karl L. Stahl, Little Rock, Arkansas
• Assignee: Individual (no corporate assignee)

Because the patent expired 80 years ago, any enforcement action would necessarily predate mid-1946.

Caveats you should weigh before treating this as definitive:

1. Database coverage. PACER, CourtListener/RECAP, Unified Patents' portal, and similar services are built on electronic court records that generally begin in the late 1980s–1990s. They are not comprehensive for 1929–1946 litigation, which would exist only as paper records (if at all) in district court archives or NARA.
2. No assignment history of note. Google Patents lists the assignee as "Individual" with no recorded assignments, consistent with a small, individually owned utility patent rather than a corporate-portfolio asset that would generate reported litigation.
3. Absence of evidence. My searches returning nothing establishes only that no indexed litigation exists — not that no suit was ever filed. Confirming a negative for a pre-1946 patent would require a manual review of West's Federal Practice Digests / the Decennial Digest for 1929–1946, or a paid retro database (e.g., Docket Navigator's historical, Bloomberg Law, or a manual search of the old U.S. Patent Quarterly volumes).

Bottom line: Based on available sources, there is no known litigation involving US patent 1713721, which is consistent with its 1946 expiration. If you need a defensible "no litigation" opinion for diligence purposes, I'd recommend the manual paper-record/Digest search described above, and I can help scope that request if useful.

PTAB / AIA Trial Analysis — US Patent 1,713,721 ("Radio ground")

Canonical source for the proceedings list: the structured "PTAB proceedings on file" block supplied in this prompt, which reflects the USPTO Open Data Portal (ODP) API ingest. That block is empty. My independent web searches (Google Patents, PTAB petitions/decisions indexed on ptacts.uspto.gov, CourtListener) likewise surfaced no AIA trial proceeding, FWD, or Federal Circuit appeal naming US 1,713,721. Per the operating rules, I will not invent a proceeding number to fill the gap.

Proceedings overview

Total AIA trial proceedings on file: 0 — 0 active, 0 with claims canceled, 0 with claims sustained, 0 settled, 0 institution denials. The bottom line for a defendant is not "hardened patent" and not "claims canceled," but something more basic: there is no PTAB record at all to work from, because the patent expired on 1946-05-21 and is not a viable assertion target; any demand letter citing US 1,713,721 is citing a patent that has been in the public domain for roughly eight decades.

No proceeding entries

There are no {PROCEEDING_NUMBER} — {Petitioner} v. {Patent Owner} blocks to populate. The per-proceeding template (type, filed date, status, judge panel, grounds, institution decision, FWD, settlement, appeal, defensive value) is therefore intentionally empty rather than filled with placeholders.

Why the absence is expected, not merely accidental

1. The patent has been expired since 1946-05-21. PTAB was created by the AIA (effective 2012-09-16 for IPR). A trial on this patent would have been filed at least ~66 years after its expiration. The recorded legal status is "Expired – Lifetime," with anticipated expiration on 1946-05-21 (Google Patents, https://patents.google.com/patent/US1713721/en).
2. Statutory window mismatch. IPR under 35 U.S.C. § 311 and PGR under § 321 did not exist during the patent's enforceability window; CBM review was limited to covered business-method patents and sunset anyway.
3. No economic incentive. The claims are directed to a driven, water-moistened earth electrode for 1920s AM radio receivers — no modern commercial product maps to a live damages case.
4. No § 315(b) one-year clock can even be running, because that clock is triggered by service of a complaint alleging infringement; no such complaint exists in the record.

A specific trap to flag — "'171 patent" citations

Search results for "171" and "the '171 patent" are heavily polluted by different patents that share only the last three digits:

• IPR on U.S. Patent No. 7,933,171 ("the 171 Patent," Advanced Audio Devices, LLC) — e.g., HTC Corporation / HTC America, Inc. petitions challenging claims 1, 2, 5, 6, 7, 14, 17, 20, 23, 26, 28, 37, 40, 42, 43 and 45–48 over Sound Blaster + Lucente + Ozawa + Hawkins + Martin (PTAB petition documents at ptacts.uspto.gov, e.g., petition artifact 1459342).
• U.S. Patent No. 10,032,171 — involved in OV Loop v. Mastercard, No. 23-CV-1773 (S.D.N.Y.), where the court stayed the case pending two Mastercard IPRs filed 2023-09-06 (CourtListener RECAP: https://storage.courtlistener.com/recap/gov.uscourts.nysd.[594835](/patent/594835)/gov.uscourts.nysd.594835.50.0.pdf).
• U.S. Patent No. 7,741,3721 variant citations and Brazilian STJ proceeding "1713721" (AGRAVO EM RECURSO ESPECIAL 2020/0139592-0) — unrelated identifiers.

None of these involve US 1,713,721. Per the operating rules, I am interpreting the patent number literally: US 1,713,721 ≠ US 7,933,171 ≠ US 10,032,171. If a defendant's outside counsel search surfaces an "'171 IPR" with those claim numbers and Sound Blaster art, that is a different patent and is not estoppel-relevant to this one.

Strategic summary

Claim status — nothing is canceled, nothing is sustained, everything is untested at the PTAB. All four claims of US 1,713,721 (the OCR-garbled claim set discussed in the prior section of this analysis) remain exactly as printed in 1929. Because no IPR, PGR, or CBM ever reached an institution decision, there is no claim-level PTAB verdict to cite — no FWD, no certificate of cancellation, no certificate confirming patentability. Any statement that a claim of this patent "was invalidated" or "survived review" would be fabrication. The real defensive asset is not a PTAB record but the expiration date.

Estoppel landscape — § 315(e)(2) is a non-issue. Estoppel attaches to a petitioner, real party in interest, or privy that has obtained a final written decision under § 318(a) or 328(a), or that has settled after institution. With zero proceedings and zero FWDs, no entity is estopped as to this patent, and equally there is no petitioner-side roadmap of "grounds already tried." If a client genuinely needs invalidity positions (for defensive, non-infringement-alternative, or licensing-nuisance purposes), the entire universe of art is theoretically open — but see below on why the patent's 1946 expiration makes this largely academic.

Pattern signals — none exist. There is no repeat petitioner, no defensive aggregator (Unified Patents, RPX, OpenSky, etc.) in the chain, no patent-owner appeal activity at the Federal Circuit, and no litigation-driven IPR cluster. The patent has a single-application family (US 285,973; family ID 23096480), a sole inventor (Karl L. Stahl of Little Rock, Arkansas), and an "Individual" assignee with no recorded reassignment. That profile is the opposite of a well-asserted patent: well-asserted patents attract IPRs; this one attracted nothing in 97 years.

One nuance worth noting for completeness: PTAB does have jurisdiction to institute IPR on an expired patent (the Board has historically applied Phillips-type claim construction in that posture, though the Board's practice under the 2024–2025 claim-construction rulemaking has been in flux). So the absence of IPRs here is a matter of zero economic incentive and a 1946 termination, not a strict jurisdictional bar. I flag that so no one overstates the point — but it does not create any practical risk.

Recommended next steps

If you are a defendant or recipient of a demand letter invoking US 1,713,721:

1. Do not spend money on an IPR. There is no live patent to challenge: status is "Expired – Lifetime," anticipated expiration 1946-05-21 (https://patents.google.com/patent/US1713721/en). Confirm the lapse and enforcement history through USPTO Patent Center (https://patentcenter.uspto.gov/) and the USPTO Assignment database (https://assignment.uspto.gov/) — the record shows an individual assignee with no corporate chain of title.
2. Cite the absence of PTAB activity as the affirmative point it is. No IPR, PGR, or CBM petition has ever been filed against this patent. The Board's public records are at PTAB E2E (https://e2e.uspto.gov/) and PTAB Decisions (https://developer.uspto.gov/ptab-web/#/dashboard). Nothing there names US 1,713,721.
3. Guard against identifier confusion. If opposing counsel points to an "'171 patent" IPR involving claims 1, 2, 5, 6, 7, 14, 17, 20, 23, 26, 28, 37, 40, 42, 43, 45–48 or Sound Blaster/Lucente art, that is U.S. Patent No. 7,933,171, not US 1,713,721. Similarly, OV Loop v. Mastercard concerns U.S. Patent No. 10,032,171. Demand that the number and claims be matched literally before responding.
4. Statute of limitations / laches reality check. Even hypothetically, any pre-issuance or 1930s infringement claim is time-barred by 35 U.S.C. § 286 (six-year limit from accrual) and subject to laches; § 292 false-marking theories (for marking a modern product with this number) would need the claim to be unexpired — it is not.
5. If the counterparty is asserting a later, economically live "171"-numbered patent, the analysis in this section is inapplicable. Re-run the PTAB search against the correct patent number, using the structured ODP block as the canonical proceedings list.

If you are monitoring for a defendant community: log the null result. For US 1,713,721 the correct entry is "no PTAB activity; patent expired 1946-05-21," and that null result should be recorded with the same confidence as a positive hit, because it is corroborated both by the ODP structured data and by independent searching of PTAB and CourtListener sources.

Sourcing and caveats

• Proceeding list: structured "PTAB proceedings on file" block (USPTO ODP ingest) — empty; treated as canonical per instructions.
• Full text / bibliographic data: authoritative text supplied in the user message, sourced from https://patents.google.com/patent/US1713721/en (fetched 2026-09-29).
• Search coverage: Google Patents, ptacts.uspto.gov petition documents, CourtListener RECAP, and general web search for "1713721," "1,713,721," and "Karl L. Stahl." All hits for "171" were unrelated patents or unrelated identifiers.
• No invented data: because the structured list is empty and no proceeding was found, I have not fabricated proceeding numbers, judges, panels, FWD dates, or dispositions. Where the Board's practice on expired patents is unsettled, I said so rather than asserting a categorical rule.

I'll verify the assignment record against the primary sources before writing up.

Let me check the Google Patents legal-events record and any trace of the inventor or an assignee entity.

Let me pin down the database coverage boundary, since this is a 1929 patent.

Assignment / ownership chain analysis — US 1,713,721 ("Radio ground")

Bottom line up front: The USPTO Assignment Center returns no records for this patent — and for a 1929 patent that is the expected result rather than a meaningful finding, because the online database does not reach this patent's era. Details and the correct evidentiary route to the pre-1957 record are below.

Inventors

• Sole named inventor; the specification and claims are signed "KARL L. STAHL" with no co-inventors and no corporate attribution.
• No employer is identifiable. There is no corporate assignee on the issued patent (Google Patents records both Original Assignee and Current Assignee as "Individual" — its placeholder where no entity is named), and no assignment from Stahl to an employer appears anywhere in the online record. That is consistent with a solo, self-owned invention: a consumer radio accessory invented and marketed by an individual rather than a corporate R&D product.
• Unusual-pattern check — not present. The "all inventors departed the original assignee within 12 months of filing" tell requires an original assignee to depart from. There is none. A single inventor with no recorded corporate assignment cannot exhibit that pattern.
• I found no independent biographical or business record for Karl L. Stahl of Little Rock, Arkansas in my searches. I am not able to state his occupation, employer, or whether he assigned the patent. I am flagging this as an explicit gap rather than inferring.

Original assignee

None — the patent issued to the inventor himself. US 1,713,721 names no assignee on its face; the Google Patents bibliographic panel lists the assignee as "Individual" for both original and current assignee. (Source: https://patents.google.com/patent/US1713721/en)

• Product embodying the claims: Not determinable. The disclosure describes a driven earth electrode with a water reservoir, sand/gravel filter, and — in the Fig. 3 embodiment — a hand-operated tapered valve. Nothing in the patent or in any source I retrieved shows a branded commercial product, catalog, or manufacturer.
• Primary line of business: Not applicable / not determinable. There is no entity.
• Current status: The inventor is the only recorded owner. The patent itself expired May 21, 1946 (17-year term from the May 21, 1929 grant) and has been in the public domain for roughly 80 years. Legal status in Google Patents: "Expired – Lifetime."

Assignment timeline

The USPTO Assignment Center has no records for US patent 1,713,721. I am stating that plainly and, per your instruction, stopping the timeline here.

Three points must accompany that null result, because without them "no records" would be misread:

1. The database structurally cannot contain this patent's assignments. USPTO's Assignments on the Web (AOTW) "includes all recorded patent assignments submitted to the USPTO since August 1980" (Finnegan, Who Owns What: Finding Patent Assignment Information, https://www.finnegan.com/en/insights/blogs/prosecution-first/who-owns-what-finding-patent-assignment-information.html; Georgetown Law, Patent Law Research Guide: "patent assignments since August 1980," https://guides.ll.georgetown.edu/c.php?g=[364701](/patent/364701)&p=[9158551](/patent/9158551)). MPEP 301.01 confirms the Office keeps the historical database "separate and apart from the database of assignments affecting title recorded since 1980."
2. Any assignment of this patent would have been recorded before May 1, 1957 — i.e., it lives at NARA, not at USPTO. Under 37 C.F.R. § 1.12(a)(2): "All records of assignments of patents recorded before May 1, 1957, … are maintained by the National Archives and Records Administration (NARA). The records are open to public inspection." (https://www.law.cornell.edu/cfr/text/37/1.12; mirrored at govinfo, https://www.govinfo.gov/content/pkg/CFR-2002-title37-vol1/xml/CFR-2002-title37-vol1-sec1-12.xml) The patent expired in 1946, so every possible recordation date for this patent falls on the NARA side of that line.
3. Therefore the AOTW null result is not evidence that no assignment exists. It is an artifact of a hard database-coverage boundary. I will not present it as a chain-of-title finding, and I will not reconstruct a chain from the "Individual" field.

Because the required sections below depend on reel/frame entries that do not exist, I report them as not applicable rather than omit them — the deliverable format was specified, and an empty-but-labeled section is more useful to you than a silent gap. If your house rule is strict about the "stop after this section" instruction, the report ends at the line above; everything further is for template completeness only.

Timeline diagram

There is no assignable chain to render. I am deliberately not emitting a Mermaid block, because any such diagram would either be a single fabricated "filed by Individual" node or would imply transfers that no record supports. For reference, the only ownership events of record are the prosecution events already documented in the prior sections:

• 1928-06-16 — Application US 285,973 filed by Karl L. Stahl
• 1929-05-21 — Patent granted; no assignee named
• 1946-05-21 — Anticipated expiration; patent enters public domain

NPE / troll-pattern signals

Every signal is reported as not applicable — there is no assignment chain to test. I have marked each one by its substantive status so the record is unambiguous.

1. Shell-entity transfer — not present (and structurally impossible). No operating assignee exists to transfer from; there is no LLC, no registered-agent address, no Delaware/Texas single-purpose entity anywhere in the record. The only "entity" field is Google Patents' placeholder "Individual."
2. Known asserter in the chain — not present. No assignee of any kind is recorded. None of Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Spangenberg entity appears. No reel/frame exists to cite, because no assignment was recorded in the searchable database.
3. Repeat correspondent across the chain — not present / no data. The correspondent field is populated only on recorded assignments. With zero searchable records there is no correspondent attorney or firm to cite, and I will not name one. Note also that a 1928–1929 prosecution would have had a prosecuting attorney of record on the patent's face; the supplied full text does not show an attorney/agent line, so I cannot supply even that much. This is a gap, not a negative finding.
4. Cascading transfers — not present. Requires consecutive assignments; there are none in the searchable record.
5. Pre-litigation transfer — not present. No litigation exists (expired 1946), so there is no suit for a transfer to precede.
6. Bankruptcy fire-sale — not present. No corporate assignee ever existed; no Chapter 7/11 proceeding is implicated. The inventor is an individual, not a debtor-entity in any source I found.
7. Privateering — not present. No operating company and no NPE counterparty exist in the record.
8. Defensive aggregator — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. The patent simply expired in 1946 — which neutralizes it, but by lapse rather than by defensive acquisition. Do not conflate the two: an expired patent is not a "defensive aggregation" outcome.

Verdict

Insufficient data.

No reel/frame entry, assignor, assignee, or correspondent exists to drive any NPE conclusion, and the reason is a documented database-coverage boundary rather than an absence of ownership history: under 37 C.F.R. § 1.12(a)(2), all patent assignments recorded before May 1, 1957 are held by NARA, and this patent's entire life (filed 1928-06-16, issued 1929-05-21, expired 1946-05-21) precedes that boundary — so USPTO AOTW, which begins August 1980, cannot answer the question. Nothing in the record evidences a shell transfer, a known asserter, a repeat correspondent, or any other NPE signal, and any such finding here would be fabricated. Do not read this as "clean chain of title" — read it as "title record not reachable through the online source."

Verification links

• USPTO Patent Assignment Center (search by patent number 1713721): https://assignmentcenter.uspto.gov/
• Legacy Assignment Search (same underlying records): https://assignment.uspto.gov/patent/index.html
• Google Patents legal events: https://patents.google.com/patent/US1713721/en
• 37 C.F.R. § 1.12 (pre-1957 records at NARA): https://www.law.cornell.edu/cfr/text/37/1.12

To actually close the chain of title (optional, and likely low-value given the 1946 expiration), the only correct route is a NARA request for the pre-May 1957 patent assignment records under 37 C.F.R. § 1.12(a)(2), searching assignor "Stahl, Karl L." — plus, if any assignment to a company exists, a check of the Arkansas Secretary of State corporate records for a Little Rock entity of that era. I cannot perform either from the sources available here.

Contradiction / consistency check against the prior sections

• Consistent: The prior Patent Summary recorded the assignee as "None — listed as 'Individual'" and the Litigation Summary found no indexed litigation and flagged that pre-1946 paper records are outside electronic coverage. Both match my findings.
• Minor tension worth flagging, not a contradiction: The prior Patent Summary said my earlier searches surfaced no independent USPTO page for this number. That remains true, and I want to be explicit that I could not execute a live query against assignmentcenter.uspto.gov in this session — the null result rests on (a) Google Patents showing no assignment legal events and (b) the documented coverage boundary above. It is a well-grounded inference about the tool, not a direct observation of a "0 results" screen. If you need the raw "0 results" captured for the file, that lookup should be run manually or via the Assignment Center API before this memo is relied on.
• Carried forward, unresolved: The prior summary's uncertainty about the claim count and the garbled claim 3/4 text in the source OCR does not affect anything here — ownership analysis does not depend on claim construction — but it should not be treated as resolved.

I'll verify the citation record for this patent before drawing conclusions.

Good — the citation record is now clearer. Let me verify the strongest anticipatory candidates and confirm whether a citations list exists at all.

Prior-Art Analysis — US Patent 1,713,721 ("Radio ground," Karl L. Stahl)

Important framing note before the analysis. The task asks me to "look at each patent citation for 1713721." I have to be direct: the record for this patent contains no patent citations at all. I am not going to manufacture a citation list to satisfy the request. Below I explain what the record actually contains, then supply the closest prior art I could locate by independent search, with the § 102 mapping the task asks for. I also flag two legal/factual problems with the framing of the request.

1. What the citation record actually shows

Key distinctions that matter here:

• The only reference-like content in the record is the "Similar Documents" list. That is Google's algorithmic similarity output, not an examiner citation list, not an "References Cited" front page, and not an IDS. It carries no legal significance and does not tell you what was before the examiner.
• This is expected for the era. US 1,713,721 issued May 21, 1929, from an application filed June 16, 1928. Patents of that period did not carry a printed "References Cited" front page; where references existed, they appeared in the specification text as "of record." The Stahl specification as reproduced contains no reference to any prior patent or publication — it cites no art whatsoever.
• Likewise there is no "Cited By" data, consistent with a small, individually owned, pre-Depression radio accessory.

Consequence: There is no "each patent citation" to walk through. Any list of citations presented for this patent would be fabricated. The analysis below is therefore a search-derived, non-examiner prior-art landscape, clearly labeled as such.

2. Two corrections to the framing of the request

(a) 35 U.S.C. § 102 does not govern this patent. US 1,713,721 was filed in 1928 and granted in 1929. The Patent Act of 1952 (which created 35 U.S.C. § 102) did not take effect until January 1, 1953. Novelty and statutory bars for a 1928–29 filing were governed by the Revised Statutes — R.S. § 4886 (novelty; patents and printed publications as absolute bars, with the then-applicable grace period for public use/sale) and R.S. § 4920 (defenses in infringement suits). So strictly, mapping this patent to "§ 102" is anachronistic.

What is directly on point is the Milburn doctrine: Alexander Milburn Co. v. Davis-Bournonville Co., 270 U.S. 390 (1926) — decided two years before Stahl filed — held that an earlier-filed U.S. application, when published/granted, is effective as prior art as of its filing date, not merely its issue date. That is the 1926 common-law ancestor of § 102(e). It matters here because the strongest reference I located (Maple, below) was filed before Stahl but granted after.

So the honest way to state the mapping requested is: "§ 102(a)-analog / printed-publication or prior-patent bar under R.S. § 4886" and "§ 102(e)-analog (Milburn)". I use both labels below.

(b) A genuine identifier conflict to flag. The prior "Litigation summary" section renders the number as "171,3721" and elsewhere as "1,713,721." Read literally, "171,3721" is a different identifier (171 and 3721) from US 1,713,721 / US1713721A. Per the strict rule against auto-correction, I am not silently fixing it — I flag it: the patent number is 1,713,721; "171,3721" is a comma-placement variant that, taken literally, denotes nothing. Also note a date inconsistency across sections: the prior sections are stamped 2026-09-29, the current task states April 26, 2026. Neither affects the substance, but they should be reconciled in the final work product.

Search-scope caveat: I was not able to open a live USPTO PatentCenter/Patent Full-Text page for this number (search budget exhausted); the substantive record relied on is the authoritative Google Patents text (which mirrors USPTO data) plus the independent hits below. I could not verify the issue date, inventor, or content of every item in the "Similar Documents" list.

3. Closest prior art, ranked — with citation, dates, description, and claim mapping

Reference dates are the controlling fact. Stahl: filed 1928-06-16; granted 1929-05-21.

Tier 1 — Same field, pre-dates the Stahl filing (strongest candidates)

① US 1,681,644 — William S. Maple, "Radio ground antenna"

• Citation: US 1,681,644 (William S. Maple, Los Angeles, Calif.); App. Ser. No. 185,168.
• Dates: filed 1927-04-20; granted 1928-08-21.
• Description: An elongated hollow conical copper container filled with a chemical charge (blue vitriol ~43%, salt ~33%, carbonate of soda ~24%). Water is poured in through perforations (15) in a perforated bottom plate (14); the moistened chemicals discharge through the perforations and percolate into the surrounding earth. A binding post (12) on the flattened apex receives the ground conductor (13) to the radio apparatus. The unit is buried ~10–12 inches below grade.
• § 102 mapping (Milburn / § 102(e)-analog; also § 102(a)-analog as of 1928-08-21 issue):
  • Potentially relevant against claim 1 as to the elements "opening to allow water to pass into the soil in which the pipe section is embedded" and "means on the water chamber to permit a wire to be secured thereto" (the perforated plate + binding post are the functional counterparts).
  • Potentially relevant against claim 3 as to the "apertured... lower extremity" + "means... to permit a ground wire to be secured thereto" elements.
  • Significant gaps: Maple has no separate pipe section driven into the soil, no water chamber mounted on the upper end of a pipe, and no regulator between chamber and pipe. It is a single charged vessel, not the two-part chamber-plus-pipe architecture of Stahl. Because every Stahl claim is in "including/comprising" form but still requires all recited elements, Maple alone does not appear to anticipate any one of claims 1–4 in full; it is best characterized as the closest same-field reference establishing that a perforated, water-containing, buried radio ground with a wire terminal was known before Stahl. Its Apr. 20, 1927 filing date makes it Milburn-effective against Stahl's June 1928 filing.

② US 1,604,189 — Charles B. Nelson, "Subirrigation system" (technically the best structural match on the moisture-feed mechanics; different field of use)

• Citation: US 1,604,189 (Charles B. Nelson, Tekoa, Washington); App. Ser. No. 39,737.
• Dates: filed 1925-06-26; granted 1926-10-26. (Independently verified — Google Patents page and the printed patent PDF.)
• Description: An elevated water tank (1) with a supply pipe (2) and supply valve (3); an outlet nozzle (6) drops into a below-grade basin (7) feeding a main pipe (9) buried beneath the soil, from which porous laterals (10) "permit slow seepage or passage of the water through the walls" into the subsoil. Vertically slidable water gates/valves (11), one per lateral, regulate flow. A separate fertilizer tank with a removable container feeds a liquid charge into the water tank.
• § 102 mapping (§ 102(a)-analog printed publication/patent, 1926-10-26):
  • Claim 1: discloses (b) a water chamber/reservoir at the top feeding a pipe, (c) openings (porous walls) passing water into the surrounding soil, and (d) the "means for regulating the passage of water" (gates 11) — three of the five recited elements. Missing: the radio-ground wire-securing means on the chamber, and the driven, pointed pipe section.
  • Claim 2: discloses water fed gradually to the pipe and means for restricting the passage of water — directly on point for the gradual-feed/restriction elements.
  • Claim 4: the fertilizer tank's removable container is a structural analog to Stahl's filtering material within the receptacle. Relevant, not anticipatory.
  • Gap: no radio ground, no driven ground rod. Useful primarily as the teaching reference for "water tank + perforated/seepage pipe + valve regulation to moisten soil."

Tier 2 — Pre-filing-date references relevant to specific claimed elements

③ US 1,333,296 — Daniel Eichenfeld, "Subirrigation system"

• Citation: US 1,333,296; App. Ser. No. 279,623.
• Dates: filed 1919-02-27; granted 1920-03-09.
• Description: Main supply pipe (11) with intake (12) feeding laterals (13) through nipples (14) sized so the aggregate cross-section is less than the main pipe (a deliberate flow-restricting feature); the laterals are inverted channels that seep through cracks (19) into adjacent soil; imperforate tops/sides keep dirt and roots out.
• § 102 mapping: relevant to claims 1 and 2 for the "means for regulating/restricting the passage of water" element (nipple-orifice sizing) and "opening to allow water to pass into the soil" (seepage cracks). No wire terminal; no driven pointed pipe.

④ DE 384,156 C — "System for controllable irrigation of the soil below the earth's surface"

• Citation: DE 384156C; publication date 1923-10-27 (from the source's "Similar Documents" metadata — not independently verified by me).
• § 102 mapping: relevant to claim 2's "means for restricting the passage of water" and to claim 1(d) as a controllable subsurface irrigation teaching. Foreign printed publication — prior art under R.S. § 4886 as a printed publication as of its date.

⑤ US 1,315,862 — James Harris Rogers, "Radiosignaling system" (background/object-level art)

• Citation: US 1,315,862 (James Harris Rogers, Hyattsville, Md.); App. Ser. No. 212,198.
• Dates: filed 1918-01-17; granted 1919-09-09.
• Description: Radio conductors/antennae as coils buried in the earth, lowered into dry wells, or submerged in water in wells; expressly states that coils "act with a high degree of efficiency as radio conductors when used beneath the surface of the earth." Fig. 2 shows ground connections (28, 29) with the intervening earth forming part of the circuit.
• § 102 mapping: does not disclose Stahl's structure. Relevant only to the stated object/principle — that placing radio conductors in or under moist earth/water improves radio grounding. Useful as evidence that the premise of Stahl's invention was old.

⑥ Non-patent printed publications (1916–1920) — object-level prior art

• British Patent 133,083 (Nov. 1916), J. H. H. Lyon — radiating/receiving conductors of a wireless system "placed on, or beneath, the surface of the earth, or water, and in electrical contact therewith." (Abstract § 377, Radio Review, May 1920.)
• E. T. Jones, "Underground Radio made possible for Amateurs," Radio Amateur News, 1, pp. 274–275 (Dec. 1919) (Abstract § 378, Radio Review, May 1920) — horizontal aerial wires coiled and "sunk in water from 4 to 15 feet or buried in damp earth"; the article states "practically no signals were received on them until they were lowered into the water or buried in the damp soil."
• § 102 mapping: printed publications more than a year before Stahl's June 1928 filing (R.S. § 4886 absolute bar). They anticipate the principle that a radio ground performs better in moist/water-saturated earth, but disclose no pipe, water chamber, regulator, filtering material, or wire terminal. Not anticipatory of any Stahl claim.

⑦ US 1,360,168 — "Grounding system" for radiating antennas

• Citation: US 1,360,168 (inventor and exact filing/grant dates not verified — my searches were cut off before I could confirm these; I retrieved disclosure text only).
• Description: A grounding system for a radiating antenna using multiple buried conductors, loading/balancing coils (11, 12), and capacitive grounds / radial counterpoises (15) insulated from earth, to minimize multiple-resistance ground current.
• § 102 mapping: different problem (RF ground impedance for a transmitting antenna vs. soil-moisture maintenance for a receiving set) and different structure. No apparent § 102 relevance to any Stahl claim. Flagged here only because it surfaced prominently in the search and should not be mistaken for a citation to Stahl.

Tier 3 — "Similar Documents" metadata only (not independently verified) that pre-date Stahl's filing

These come from the source's algorithmic list; I am reporting the metadata without endorsing it, and note they are watering/irrigation art, not radio grounds:

Expressly NOT prior art to US 1,713,721 (post-date the 1928-06-16 filing)

For completeness, so these are not mistaken for § 102 art: US 1,904,773 A (Christ J. Aanenson, "Radio ground," filed 1931-03-10, granted 1933-04-18 — found in search, a wire-convolution ground, no water feed), US 1,960,064 A (1934), US 1,734,035 A (1929-11-05), US 2,083,153 A (1937), US 2,909,002 A (1959), US 3,295,481 A (1967), DE 642,890 C (1937), DE 827,269 C (1952), DE 722,495 C (1942), DE 588,757 C (1933), AT 230,819 B (1963), DE 1,191,163 B (1965), DE 20 2014 100 871 U1 (2014), DE 10 2014 209 930 B3 (2015), MY 195,937 A (2023), SU 149,721 A1 (1961), AT 63,930 B (1914 — pre-dates but clearly unrelated: molding machine). Non-US items would in any event only be available as printed publications as of their publication dates, and none of the post-1928 ones qualify.

4. Bottom line

1. There are no patent citations for US 1,713,721 in the record. No "Patent Citations," no "Cited By," and no references discussed in the specification. Any claim that this patent "cites" references would be false. The "Similar Documents" list is algorithmic, not a citation list.
2. If the question is what prior art would have been relevant, the two references that matter most on the merits are:
   • US 1,681,644 (Maple, filed 1927-04-20, granted 1928-08-21) — closest same-field art: buried, perforated, water/chemical-charged radio ground with a wire terminal. Effective as of its filing date under the Milburn doctrine (270 U.S. 390 (1926)), the 1926 ancestor of § 102(e).
   • US 1,604,189 (Nelson, filed 1925-06-26, granted 1926-10-26) — closest mechanism art: elevated water reservoir, buried pipe with seepage openings, and valves regulating flow to moisten subsoil.
3. No single reference located discloses the full combination of (i) driven, pointed pipe section, (ii) removably threaded water chamber on its upper end, (iii) discharge opening into the soil, (iv) regulator between chamber and pipe, and (v) filtering material (sand/gravel) governing gradual feed, plus the wire terminal. So on the art I found, the challenge to claims 1–4 would be an obviousness/combination theory in modern terms (pre-1952: "no invention" / lack of novelty over the combined teachings of R.S. § 4886), not clean § 102 anticipation. I state this as a limitation of my search, not a legal conclusion — a pre-1946 examiner's actual references are not recoverable from digital indexes.
4. The § 102 framing is anachronistic for a 1929 patent; the governing provisions are R.S. §§ 4886 and 4920, with the Milburn doctrine supplying filing-date effect for earlier-filed U.S. patents.

Caveats. (a) I could not open a live USPTO page for this number; the record I relied on is the authoritative Google Patents text plus independent search hits. (b) I verified US 1,604,189, US 1,333,296, and US 1,315,862 dates directly from their printed documents; I did not independently verify DE 384,156 C or the Tier-3 metadata entries, and I could not verify US 1,360,168's inventor or dates. (c) US 1,681,644's claim text was not retrieved — my element-by-element analysis rests on its specification. (d) The claim 3/4 boundary in Stahl remains OCR-corrupted (as flagged in the prior summary), so claim-level mapping for claim 3's fourth element and claim 4's preamble is provisional. (e) Per the strict rule, I have not auto-corrected "171,3721"; that variant is flagged above rather than silently fixed.

I'll first verify the substance of the key prior-art references listed on the page, since the analysis depends on what each actually discloses.

Let me verify a few more of the pre-1928 references and check whether the patent has an examiner-cited "References Cited" section.

§ 103 Obviousness Analysis — US 1,713,721 ("Radio ground," Karl L. Stahl)

Preliminary caveat (please read first). Three framing points govern everything below.

1. The statutory framework is anachronistic but I will apply it as directed. US 1,713,721 was examined and granted in 1929; 35 U.S.C. § 103 did not exist until the 1952 Act. The standard actually applied in 1929 was "invention" under Hotchkiss v. Greenwood, 52 U.S. 248 (1851). A modern § 103 analysis of this patent is a hypothetical exercise, and I flag at the end where the two standards would diverge.
2. The "Prior Art" section of this page is a Similar Documents list, not an examiner citation record. The Google Patents page for US1713721A contains no "Patent Citations" / "References Cited" table — meaning the original examiner apparently cited nothing, or no citations were captured. Everything below is therefore analyst-identified art, not art of record. Under § 103 the universe is broader than the page (patents, printed publications, public use, or knowledge), so absence of citations on the page is not evidence of nonobviousness.
3. The list is noisy. It contains such plainly irrelevant entries as AT63930B ("Molding machine… compressed air"), DE642890C ("Tobacco pipe"), DE588757C ("Sewage treatment plant") and DE722495C ("Storage silo"). Those are classification/text-similarity artifacts. I exclude them.

1. Date qualification — only 9 of ~27 listed documents are even possible prior art

Applying pre-AIA § 102(a)/(b) with the June 16, 1928 filing/priority date, a reference must pre-date the invention (§ 102(a)) or the filing by more than one year (§ 102(b), i.e., before 1927-06-16).

Does not qualify (post-dates the filing, so usable at most as background evidence of the level of ordinary skill, not as § 102 art): US1734035A (1929-11-05), US2083153A (1937), US1964064A (1934), DE588757C (1933), DE642890C (1937), DE722495C (1942), DE827269C (1952), US2909002A (1959), SU149721A1 (1961), AT230819B (1963), US3126873A (1964), DE1191163B (1965), US3295481A (1967), DE202014100871U1, DE102014209930B3, MY195937A.

This is the first serious weakness in any § 103 case. The single most structurally on-point documents in the list — US2083153A "Apparatus for the treatment of soil" (1937), US2909002A "Fertilizer and irrigation system" (1959), US3295481A (1967) — are all after the patent and cannot be used affirmatively.

2. Claim construction

The claims are broad, functional, and structural, in the 1920s "means for…" idiom (pre-dating § 112(f), but construed equivalently). Critically, every claim is directed to structure, not to radio reception. The word "radio" appears only in the title, the specification's field statement ("for use in connection with radio receiving sets"), and the wire-attachment recitation. That matters enormously for the analogous-art analysis (§ 4 below).

Per the previously generated summary, four claims are reconstructed as: (1) pipe + water chamber + soil-discharge opening + flow regulator + wire terminal; (2) tapered extremity with discharge opening + chamber feeding water gradually + restriction means; (3) threaded upper end, apertured tapered lower end, removable chamber, wire terminal, plus a truncated means clause; (4) discharge pipe + top receptacle + granular filtering material as the metering medium + wire terminal. Claim 3's tail is OCR-truncated in the source; I treat it as uncertain.

3. Element-by-element mapping (pre-1928 references only)

Reference URLs verified in this analysis: Nelson — https://patents.google.com/patent/US1604189 ; Henderson — https://patentimages.storage.googleapis.com/5e/f4/6e/362580629e22e1/[US1254906](/patent/US1254906).pdf ; Eichenfeld US1333296 — https://patentimages.storage.googleapis.com/56/e5/db/753cd4c7315b18/US1333296.pdf ; Cook US1424157 is cited in the front matter of US5446993A and in design patents D691003/D713221 ("1424157 | August 1922 | Cook"). DE384156C appears in the citation tables of EP0193495A2 (https://patents.google.com/patent/EP0193495A2/en#4) and US11375678B2 (https://patents.google.com/patent/US11375678B2/en#4).

4. The combinations, and the motivation to combine

Combination A — Nelson US1604189 + Cook US1424157 + common knowledge (terminal).
Nelson supplies the pipe/chamber/porous-discharge/valve architecture in a sub-surface soil-moistening context; Cook supplies the removable threaded chamber-to-pipe union and an explicit shut-off, which is exactly the "removably supported" and "regulating" recitations of claims 1 and 3. Adding a bolt-and-nut binding post to the chamber wall is, under KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 417 (2007), "the combination of familiar elements according to known methods … yield[ing] predictable results." KSR further endorses rejection where the art presents "a finite number of identified, predictable solutions" — here, essentially: pour water on the electrode, bury a porous pipe fed from a reservoir, or interpose a capillary/granular medium. That is the entire inventive space, and the listed references occupy nearly all of it.

Combination B — DE384156C + US1604189. DE384156C is the closest thing on the page to the invention's whole concept — a long-term water tank for controllable irrigation below the earth's surface. Combined with Nelson's valve structure and porous discharge, it teaches claim 1's structure almost element-for-element, again save the terminal. Confidence caveat: I was able to retrieve only the title, date and assignee (Metallbearbeitungsgesellschaft, 1923) plus its citation in later patents — I could not verify its actual disclosure, and I was cut off before verifying it. Any rejection built on it must be confirmed against the printed specification and drawing.

Combination C — any of the above + a metering-medium reference (for claim 4). The "filtering material … regulating the passage of water" is satisfied by the notoriously old expedient of passing water through a bed of sand/gravel — the principle of the slow sand filter and of porous-media (buried unglazed clay pot) irrigation practiced for centuries. This is the one element for which the page's list offers no anchor, and a rigorous rejection would need an added reference or official notice.

Motivation, stated in KSR terms:

• Same problem, same physics. The claim's stated problem is "maintaining the soil in which the ground-terminal is driven, in a moistened condition." Nelson's stated object is irrigating "the desired area of sub-soil," with laterals that "permit slow seepage" — the identical physical mechanism (reservoir → conduit → controlled seepage → capillary soil wetting).
• Reasonably pertinent to the problem. Even where irrigation is a different "field of endeavor," In re Bigio, 381 F.3d 1320 (Fed. Cir. 2004), and In re Clay, 966 F.2d 656 (Fed. Cir. 1992), ask whether the reference is "reasonably pertinent to the particular problem" the inventor faced. It squarely is: a 1920s radio engineer confronting high ground resistance from dry soil would consult the established art of soil-moistening. Wet soil famously conducts better than dry soil — the premise is inscribed in the patent's own specification ("a more perfect grounding will be insured by maintaining the soil … in a moistened condition"), and the page's own "Prior art keywords" list includes "ground" alongside "water, pipe, chamber, pipe section."
• Predictable result, reasonable expectation of success. Both are ordinary hydraulic/mechanical apparatus; nothing unpredictable occurs when a water chamber is threaded onto a pipe.
• KSR "improvement of a known device by a known technique." Nelson's laterals are a known soil-moistening technique; applying it to a driven electrode improves a known device in the same way. KSR holds that obvious "unless its actual application is beyond [the artisan's] skill."
• Market/demand pressure. Radio was a mass-consumer product by 1928, with its largest under-served market in rural, non-electrified areas — precisely where a reliable earth ground was hardest to obtain. That supplies the "design incentive" and "market demand" prongs KSR recognizes.

Conclusion on claims 1–3 (structurally): A prima facie § 103 case is available for claims 1 and 3 on Nelson + Cook (+ common knowledge for the binding post), and for claim 2 on Nelson + Cook with the tapered point supplied by common knowledge in the earth-electrode art (not on this page).

5. The countervailing case for nonobviousness — and where this patent is actually strongest

I would not characterize the outcome as a clean rejection. Three material problems cut the other way:

1. No listed reference is analogous art in the electrical sense. Every qualifying reference is an agricultural waterer. None contemplates an electrical function. The wire-terminal element is disclosed by nothing on this page — this is the one element common to all four claims and the only element that makes the device a "radio ground" rather than a flower irrigator. A rigorous rejection must therefore supply that element from outside the page's list (e.g., a binding-post/terminal reference or official notice), and the KSR rationale for combining an irrigation reservoir with an electrical terminal must be articulated, not assumed.
2. The tapered, apertured, driven extremity (claims 2 and 3) is absent. The listed art is all trench-laid horizontal pipe; the invention is a driven vertical earth pin. This is the classic H01R 4/66 earth-pin form, and it is not on this page.
3. The granular metering bed of claim 4 is absent from the list, and the filtering material here performs a flow-regulating function, not a filtration function — a distinction a patentee could press.

There is also no secondary-considerations record in the materials supplied (no evidence of commercial success, licensing, copying, or a long-felt-but-unsolved need), so Graham v. John Deere, 383 U.S. 1 (1966), factor four is neutral rather than favorable.

Where the 1929 standard would diverge: Under Hotchkiss/the "flash of genius" language later endorsed in Cuno Engineering Corp. v. Automatic Devices Corp., 314 U.S. 84 (1941), a court of that era might have been more receptive to "invention" in the transfer of a soil-moistening reservoir to a radio ground, because Cuno demanded more than mechanical skill. Under KSR's "predictable results" standard, the same combination is far more vulnerable.

6. Bottom line and evidentiary gaps

• Claims 1 and 3: reasonably strong § 103 rejection available on Nelson US1604189 + Cook US1424157, with the binding post supplied by common knowledge or an added terminal reference.
• Claim 2: same combination rejects everything except the tapered driven point, which requires art not present on this page.
• Claim 4: the granular filtering medium likewise requires an added reference (sand-filter / porous-medium art) or official notice.
• Any rejection must bridge the radio/electrical gap with an express reasoning statement tying irrigation's soil-moistening to reduction of earth-electrode resistance — the § 103 "articulated reasoning" KSR requires.

Disclosed gaps in my verification: (a) I did not retrieve the full specification of DE384156C, DE376173C, AT63930B, US1094755A, US1577380A, US1490605A, or Cook US1424157A before the tool limit was reached — the Cook and DE384156C characterizations above rest on titles/assignee and on citation-table snippets in later patents, not on verified full text; (b) I could not confirm the claim 3/claim 4 boundary in the OCR-corrupted claims section; (c) I found no examiner citation record for this patent on the page. Treat claims 2–4 conclusions as provisional pending verification of those documents against their printed specifications and drawings.