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Archaic Legal Glossary & Citations

“Letters Patent”14th–20th Century
19th-C Meaning:

Open public letters from a monarch or government (literae patentes) granting monopoly rights.

Modern Engineering Decoded:Issued USPTO utility or design patent publication.
Historical note: Contrasted with 'letters close' (private sealed royal correspondence).
“In testimony whereof”19th Century
19th-C Meaning:

Formal concluding legal formula affirming under oath the execution of the instrument.

Modern Engineering Decoded:Inventor and witness digital/physical signatures.
Historical note: Required two witness attestations in 19th-century USPTO filing procedure.
“Aeroplane”Early 20th Century (Wright era)
19th-C Meaning:

A flat or cambered lifting aerofoil surface supported dynamically by air pressure.

Modern Engineering Decoded:Wing / Airfoil lifting surface (later evolved to mean the entire motorized aircraft).
Historical note: The Wrights used 'aeroplane' to denote the individual fabric-covered wings.
“Undulating Current”19th Century (Bell era)
19th-C Meaning:

An electric current whose magnitude varies continuously and periodically without interruption.

Modern Engineering Decoded:Continuous analog AC or audio-frequency electrical waveform.
Historical note: Bell's central legal weapon against telegraph companies who relied on pulsed DC make-and-break circuits.
“Subdivision of the Electric Light”1870s–1880s (Edison era)
19th-C Meaning:

The problem of operating numerous small domestic lamps off a single electrical generator.

Modern Engineering Decoded:Parallel circuit wiring of high-resistance incandescent electrical loads.
Historical note: Pundits claimed it was physically impossible until Edison increased filament resistance to 100 ohms.
“Optically Anisotropic Solution”1960s (Kwolek era)
19th-C Meaning:

A liquid solution that exhibits direction-dependent refractive indices due to molecular alignment.

Modern Engineering Decoded:Liquid crystalline nematic phase polymer dope.
Historical note: Technicians initially tried to throw out Kwolek's cloudy solution thinking it was contaminated.
“Unitary Body of Semiconductor Material”1950s–1960s (Noyce era)
19th-C Meaning:

A single continuous crystal structure of silicon or germanium.

Modern Engineering Decoded:Monolithic single-crystal silicon die / integrated circuit wafer.
Historical note: Differentiated Noyce's monolithic planar circuit from Jack Kilby's hybrid flying-wire prototype.
“Peculiar and Novel Construction”19th Century
19th-C Meaning:

A distinctive, patentable structural arrangement not found in prior art.

Modern Engineering Decoded:Novel and non-obvious mechanical embodiment under 35 U.S.C. § 103.
Historical note: Standard 19th-century legal terminology establishing novelty.

Museum Broadside & Archival Print Edition

Authentic archival layout formatted for framing, study, and high-resolution printing

Paper:
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The United States Patent & Trademark Archive

Historical Specification & Engineering Broadside

Curated, Verified & Restored by Classic Patents (classic-patents.com)
ELECTRICAL TRANSFORMERA spiral secondary winding that keeps adjacent turns near one another in potential while moving the high-potential terminal away from the primary.
US 593,138Class: H01F 38/00 (transformers; resonant coils)
Inventor(s):Nikola Tesla
Origin / Location:New York, N.Y.
Grant & Filing:Filed March 20, 1897 · Granted November 2, 1897

I. Historical Context & Grant Summary

Tesla's 1897 transformer arranges primary and secondary windings so the secondary's greatest potential is remote from the primary and adjacent turns have a small voltage difference. The grant also describes paired step-up and step-down transformers for transmission.

II. Core Mechanism & Scientific Principles

The problem addressed here is insulation, not a generic spark-coil recipe. Tesla arranges the winding so that neighboring turns have relatively little voltage between them, while the terminal at the greatest potential is physically remote from the primary and from a person handling the apparatus.

Physical Operation:A secondary coil is wound as a flat spiral or another graded form. Its inner end, nearest the primary, is electrically connected to the primary and to earth in use. The remote end reaches the highest potential. Tesla also describes a transmission pair: a sending transformer raises the line potential and a receiving transformer lowers it again.
Governing Formulation:
Voltage grading along a winding:The voltage between adjacent turns is the difference between their local potentials.
Standing-wave length described by the specification:Tesla specifies a secondary approximately one quarter of the electrical disturbance wavelength.

III. The Granted Legal Monopoly (Key Claims)

Claim 1 (Independent)primary-secondary connection

Claims a high-potential transformer having primary and secondary coils, with one secondary terminal electrically tied to the primary and, during operation, to earth. The claim makes that specified three-way relationship the legal limitation, without requiring the later flat-spiral geometry.

Claim 2 (Independent)flat spiral winding

Claims the same high-potential transformer when its primary and secondary are wound as a flat spiral. It specifically fixes the secondary end nearest the primary as the end electrically connected both to the primary and, in use, to earth.

Claim 3 (Independent)nested spiral geometry

Claims a spiral arrangement in which the secondary lies inside and is surrounded by the primary turns. The secondary terminal adjacent to the primary must be electrically connected both to that primary and, while in use, to earth; that nested placement distinguishes this claim from the broader first claim.

IV. Mechanical Organ Breakdown

Graded Secondary WindingTerm: “convolutions” → winding turns

The secondary's geometry separates the high-potential terminal from the primary and keeps neighboring turns closer in potential.

Primary and Earth ConnectionTerm: “earth” → protective ground connection

The secondary terminal adjacent to the primary is connected to the primary and, in use, to earth.

Transmission PairTerm: “” →

A sending transformer raises potential for a line, and a receiving transformer lowers it for lamps, motors, or another local circuit.

CLASSIC PATENTS DIGITAL ARCHIVE • PERMANENT EXHIBIT ID: us-593138-tesla-coil
classic-patents.com/patents/us-593138-tesla-coil
Original USPTO PDF
Classic Patents/US 593,138
Electrification Era (1880–1900)High-Potential Electrical Transmission

Tesla's High-Potential Transformer

US 593,138

A spiral secondary winding that keeps adjacent turns near one another in potential while moving the high-potential terminal away from the primary.

Inventor(s)Nikola Tesla
Grant DateNovember 2, 1897
Filing DateMarch 20, 1897
LocationNew York, N.Y.
Tesla's 1897 transformer arranges primary and secondary windings so the secondary's greatest potential is remote from the primary and adjacent turns have a small voltage difference. The grant also describes paired step-up and step-down transformers for transmission.
USPTO PDF
Audio Engineering Breakdown~1 min listen

Listen to the narrated mechanical breakdown and civilizational context

Engineering Analysis & Physical Principles

How It Works: Step-by-Step Mechanical & Physical Breakdown

The problem addressed here is insulation, not a generic spark-coil recipe. Tesla arranges the winding so that neighboring turns have relatively little voltage between them, while the terminal at the greatest potential is physically remote from the primary and from a person handling the apparatus.
The Core Breakthrough Mechanism

A secondary coil is wound as a flat spiral or another graded form. Its inner end, nearest the primary, is electrically connected to the primary and to earth in use. The remote end reaches the highest potential. Tesla also describes a transmission pair: a sending transformer raises the line potential and a receiving transformer lowers it again.

Interactive Real-Time Physical Simulation

Drag to rotate · Pinch to zoom · Shared controls update the displayed model
INITIALIZING THREE.JS WEBGL SIMULATION...
Distributed-Wave Transformer Geometry.
Host-Model Telemetry/Computed Readout
Distributed-Wave Transformer Geometry
Electrical Length
90.0deg[1]
Quarter-Wave Target
50.00mi[1]
Wire-Length Error
0.00mi[1]
Absolute Potential
UNDERDETERMINEDsource boundary[1]
Required Quarter-Wave Length
∂l_{1/4} / ∂f (host sensitivity)
-0.05405405405405406 mi / Hz at 925 Hz
Electrical Disturbance Frequency925 Hz
Developed Secondary Wire Length50 mi
Interval ghosts
βl90.0 deg · [45, 180]
Fidelity / MMS residual
Quarter-wave length vs Tesla's printed 925 Hz example
model50.000000 mi
reference50.000000 mi
residual0.000000 mi
Spectral modes
Dated scenarios

Detailed Component Architecture

1Graded Secondary Winding
The secondary's geometry separates the high-potential terminal from the primary and keeps neighboring turns closer in potential.

The specification identifies a flat spiral as the usual form and permits a frustum-of-cone form. Its stated safety rationale is that potential rises along the winding while the difference between adjacent turns remains comparatively small.

19th-C. Term: convolutionsModern: winding turns
2Primary and Earth Connection
The secondary terminal adjacent to the primary is connected to the primary and, in use, to earth.

Claims 1 through 3 make this electrical relationship part of the claimed transformer. The source says it reduces the tendency for sparks to jump between adjacent primary and secondary portions.

19th-C. Term: earthModern: protective ground connection
3Transmission Pair
A sending transformer raises potential for a line, and a receiving transformer lowers it for lamps, motors, or another local circuit.

Figure 1 depicts this system-level arrangement. Claim 4 covers the relationship between the two transformers and the line and earth terminals of their longer, fine-wire coils.

Engineering Principles & Equations

Governing Equations & Engineering Principles

Authored explanation paired with its stated mathematical relation

Claimed Common Node & Adjacent-Turn Grading

High-Voltage ElectromagneticsClaim 1
Mathematical Governing Law
Terms:
Plain English DecoderHover or tap any highlighted phrase
The , the , and share one node; the graded winding keeps the small relative to the total terminal-to-earth difference.
V(B0)V(B_0)
Adjacent Secondary-End Potential
Potential at the secondary terminal physically adjacent to the primary
Volts (V)

Claims 1 through 3 electrically connect this terminal to the adjacent primary terminal and, in use, to earth.

Physical Principle & Engineering Insight

This relation separates what the grant fixes exactly (the common electrical node) from what it describes qualitatively (small adjacent-turn differences). Absolute voltages remain underdetermined.

Historical Context: Claim 1 establishes the common-node connection; Claims 2 and 3 add the flat or nested spiral geometry that moves the remote high-potential terminal away from the primary.

Quarter-Wave Stationary-Wave Distribution

High-Frequency ResonanceClaim 1
Mathematical Governing Law
Terms:
Plain English DecoderHover or tap any highlighted phrase
The is tuned to approximately one-quarter of the , equal to the divided by four times the .
ℓ\ell
Developed Secondary Wire Length
Total developed wire length of the secondary spiral
Meters (m)

Tesla specifies that the wire length should match one-quarter of the electrical wavelength so that a voltage antinode (maximum potential) develops at the free terminal.

Physical Principle & Engineering Insight

The source fixes the terminal-potential endpoints: zero at the common primary / earth end and maximum at the remote end. It does not print current magnitude, impedance, loss, or load data.

Historical Context: The grant prints a directly checkable example: 925 disturbances per second at 185,000 miles per second gives a 200-mile wavelength and a 50-mile quarter-wave secondary.

Voltage grading along a windingAuthored Principle 1
Stated relation

The voltage between adjacent turns is the difference between their local potentials.

The historical claim is architectural: distribute the change in potential along a long winding rather than allowing a large change across closely adjacent conductors.
Standing-wave length described by the specificationAuthored Principle 2
Stated relation

Tesla specifies a secondary approximately one quarter of the electrical disturbance wavelength.

Tesla specifies a secondary length approximately one-quarter of the electrical disturbance wavelength so the remote terminal is at maximum potential. The manual edition preserves and explains the source's numerical example.

Interactive Schematic Sheet (Fig. 1)

The first drawing sheet shows the primary and secondary windings in a transmission arrangement with a dynamo, lamps, and motors.

1.00x
US 593,138 · FIG. 1remote high terminalBCcommon / earth
Tap any numbered pin3 Curated Callouts
Callout Pin Inspector

Select Any Numbered Pin

Click pins on the schematic or select from the list below to inspect historical specifications.

Why It Still Matters

This patent records a high-potential transformer design whose insulation strategy is geometric and system-level. The complete source reading retains Tesla's terminal arrangement, quarter-wave example, and Figure 1 to 3 constructions beside their precise modern companions.

Legal Claims Decoder (4 Numbered Claims)

Compare dense legalistic claims directly with decoded plain-English functional specifications.
Claim #1Independent Master Claim
1/4
Verbatim Historical Legal Text
“A transformer for developing or converting currents of high potential, comprising a primary and secondary coil, one terminal of the secondary being electrically connected with the primary, and with earth when the transformer is in use, as set forth.”
Plain English Engineering Translation
Claims a high-potential transformer having primary and secondary coils, with one secondary terminal electrically tied to the primary and, during operation, to earth. The claim makes that specified three-way relationship the legal limitation, without requiring the later flat-spiral geometry.
Key Protected Innovations:
primary-secondary connectiongrounded secondary terminal

The Historical Bottleneck

Tesla describes earlier transformer and induction-coil construction as unable to produce or practically use the required high potentials without danger to apparatus or people.

Why Prior Art Failed

  • •Ordinary winding arrangements placed conductors with large potential differences too near each other.
  • •A high-potential line could discharge to nearby grounded objects without adequate insulation and support.
The Breakthrough Insight
“Make the potential gradient a property of the winding geometry and terminal arrangement, then use paired transformers to raise and lower potential across a transmission line.”
After the Grant
The complete manual source edition is prepared against the four-sheet facsimile; independent facsimile and live-route acceptance remains a separate root quality-control step.
Civilizational Impact
The source documents a practical concern central to high-voltage engineering: insulation coordination between winding turns, terminals, lines, and ground.
Technological Lineage & Descent

The Polyphase Electric Grid

From Direct-Current Motors to Resonant Alternating Power Systems

The electrical revolution that replaced localized chemical galvanic cells and direct current with universal polyphase induction motors and high-voltage transmission.

1837First Rotary Electric Motor
US 132

Davenport Contact-Plate Electric Motor

Commutator-switched electromagnets creating continuous rotary motive torque.

1871Continuous DC Dynamo
US 120,057

Gramme and d’Ivernois Endless-Bobbin Dynamo

Closed-ring continuous toroidal armature eliminating pulsating current ripple.

1880High-Resistance Parallel Grid
US 223,898

Edison's High-Resistance Carbon Lamp

High-resistance carbon filament in high vacuum enabling parallel circuit distribution.

1888Rotating Magnetic Field
US 381,968

Tesla Progressive Alternating-Current Motor

Independent out-of-phase AC currents inducing rotor torque without brushes or sparks.

1897Resonant High-Frequency TransformerThis Patent
US 593,138

Tesla's High-Potential Transformer

Air-core loosely coupled resonant LC circuits generating high-potential oscillations.