Claim register
Claim Evaluation
Every claim is stated exactly, traced to its origin, and evaluated against the best supporting and the best opposing case. Scientific claims must expose their full reasoning chain — observation, measurement, calculation, prediction, physical test, result, replication — and declare per-model predictions BEFORE the result is shown. Appeals to authority (“science says”, “experts agree”, “the math proves it”, “settled”) are not evidence. Confidence is authored, not tallied. Preserve disagreement rather than force a conclusion.
The Gleason map's coastline geometry matches an azimuthal-equidistant projection of a spherical earth
SupportedThe observed coastline layout on Gleason's 1892 map is consistent with — not evidence against — a north-polar azimuthal-equidistant projection of a spherical earth.
Origin: Direct comparison in this lab's Projection view.
Best supporting case
Rendering Natural Earth coastlines under a modern d3-geo azimuthal-equidistant centered on 90°N produces the same continental placement Gleason shows.
Best opposing case
One could argue the projection is a literal chart of a flat earth. That interpretation is a separate cosmological claim not decided by the projection identity.
Evidence
[supports] observation Mathematical calculation — Side-by-side render in the Projection Lab shows matching outlines within Natural Earth 1:110m accuracy.
- ↳ Natural Earth 1:110m Physical Coastline (Reference)
- ↳ d3-geo / d3-geo-projection projection implementations (Reference)
[supports] source statement Historical document — The patent names the construction that produces that geometry.
- ↳ US Patent 497,917 — Map of the World (Alexander Gleason) (Government)
Circular-reasoning check
No circular-reasoning risks identified in the authored evidence chain.
Hidden assumptions
- The comparison assumes Natural Earth 1:110m is an accurate coastline at that scale — it is, within documented tolerances.
- The comparison establishes projection identity only, not cosmology.
Missing evidence
- A pixel-accurate georeferenced overlay of the archival scan against the d3 render, with explicit control points and residuals.
Contradictions
— none recorded —
Reproducibility
- Directly reproducible in the Projection Lab.
Confidence · moderate
The math is straightforward, but a rigorously georeferenced overlay would move this from moderate to high.
Confidence is authored, not tallied. It reflects primary vs. secondary evidence, source independence, methodology, conflicts, and reproducibility — not the count of sources.