On the Measurement of the Earth
E728495
"On the Measurement of the Earth" is an ancient treatise in which Eratosthenes used geometric reasoning and observations of the Sun to calculate the Earth's circumference with remarkable accuracy.
All labels observed (1)
| Label | Occurrences |
|---|---|
| On the Measurement of the Earth canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T8345737 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: On the Measurement of the Earth Context triple: [Eratosthenes, notableWork, On the Measurement of the Earth]
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A.
On the Sizes and Distances of the Sun and Moon
On the Sizes and Distances of the Sun and Moon is an ancient Greek astronomical treatise that presents one of the earliest known geometric attempts to quantify the relative sizes and distances of the Sun and Moon from Earth.
-
B.
Cosmographiae Introductio
Cosmographiae Introductio is a 1507 Latin cosmography book, best known for introducing and popularizing the name "America" for the newly discovered Western Hemisphere.
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C.
Theory of the Earth
Theory of the Earth is James Hutton’s foundational geological work that introduced the concept of deep geological time and laid the groundwork for modern geology.
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D.
On the Measurement of the Circle
On the Measurement of the Circle is a mathematical treatise by Archimedes in which he rigorously approximates the value of π and explores properties of circles.
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E.
The Sand Reckoner
The Sand Reckoner is a treatise by Archimedes in which he develops a system for expressing extremely large numbers to estimate the quantity of sand that could fit in the universe.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: On the Measurement of the Earth Target entity description: "On the Measurement of the Earth" is an ancient treatise in which Eratosthenes used geometric reasoning and observations of the Sun to calculate the Earth's circumference with remarkable accuracy.
-
A.
On the Sizes and Distances of the Sun and Moon
On the Sizes and Distances of the Sun and Moon is an ancient Greek astronomical treatise that presents one of the earliest known geometric attempts to quantify the relative sizes and distances of the Sun and Moon from Earth.
-
B.
Cosmographiae Introductio
Cosmographiae Introductio is a 1507 Latin cosmography book, best known for introducing and popularizing the name "America" for the newly discovered Western Hemisphere.
-
C.
Theory of the Earth
Theory of the Earth is James Hutton’s foundational geological work that introduced the concept of deep geological time and laid the groundwork for modern geology.
-
D.
On the Measurement of the Circle
On the Measurement of the Circle is a mathematical treatise by Archimedes in which he rigorously approximates the value of π and explores properties of circles.
-
E.
The Sand Reckoner
The Sand Reckoner is a treatise by Archimedes in which he develops a system for expressing extremely large numbers to estimate the quantity of sand that could fit in the universe.
- F. None of above. chosen
Statements (42)
| Predicate | Object |
|---|---|
| instanceOf |
ancient scientific treatise
ⓘ
work on astronomy ⓘ work on geodesy ⓘ |
| angleApproximation | about one-fiftieth of a full circle ⓘ |
| angleMeasured | difference in solar elevation between Syene and Alexandria ⓘ |
| assumption |
Sun is very far from Earth
ⓘ
Syene and Alexandria lie approximately on the same meridian ⓘ distance between Syene and Alexandria is known ⓘ |
| author | Eratosthenes NERFINISHED ⓘ |
| basedOnObservation |
solar altitude at Alexandria
ⓘ
solar altitude at Syene ⓘ |
| calculationType | circumference from central angle and arc length ⓘ |
| distanceSegment | Syene–Alexandria arc NERFINISHED ⓘ |
| field |
astronomy
ⓘ
geodesy ⓘ geometry ⓘ |
| genre | scientific prose ⓘ |
| historicalPeriod | Hellenistic period NERFINISHED ⓘ |
| influenced |
history of geography
ⓘ
later estimates of Earth's size ⓘ later geodesy ⓘ |
| influencedBy | earlier Greek geometry ⓘ |
| keyConcept |
angle of the Sun at local noon
ⓘ
parallel rays of sunlight ⓘ proportionality between arc length and central angle ⓘ spherical Earth ⓘ |
| knownFrom |
Cleomedes' writings
ⓘ
accounts by later authors ⓘ |
| language | Ancient Greek ⓘ |
| mainSubject |
Earth
NERFINISHED
ⓘ
Earth's circumference ⓘ |
| measurementUnit | stadion ⓘ |
| notableFor |
early quantitative measurement of a planetary body
ⓘ
remarkable accuracy of Earth's circumference estimate ⓘ |
| placeOfOrigin | Alexandria NERFINISHED ⓘ |
| preservationStatus | survives only in later reports ⓘ |
| relatedWork | Geographika NERFINISHED ⓘ |
| result | approximate value for Earth's circumference ⓘ |
| scientificSignificance |
demonstration of Earth's large but finite size
ⓘ
early example of empirical Earth measurement ⓘ |
| usesMethod |
geometric reasoning
ⓘ
observation of the Sun ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: On the Measurement of the Earth Description of subject: "On the Measurement of the Earth" is an ancient treatise in which Eratosthenes used geometric reasoning and observations of the Sun to calculate the Earth's circumference with remarkable accuracy.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.