the.co.im/gleason/ — credits and rights
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THE MAP
  Gleason's New Standard Map of the World, Alexander Gleason, Buffalo
  Electrotype and Engraving Co., Buffalo N.Y., 1892.
  Scan: Norman B. Leventhal Map & Education Center at the Boston Public Library
  https://ark.digitalcommonwealth.org/ark:/50959/7h149v85z
  Digital Commonwealth image commonwealth:7h149v867, call number G3201.B71 1892 .G54x
  (The credit is not required; it is given.)

  Rights, as the record states them:
    No known copyright restrictions.
    No known restrictions on use.

  Digital Commonwealth's download terms, verbatim (read 2026-09-15):
    Please review the terms of use for this item: No known copyright
    restrictions. No known restrictions on use. Notice: This digital file may be
    subject to copyright law of the United States (Title 17, U.S. Code) governing
    the making of reproductions of copyrighted material. The person using this
    content may be liable for any infringement.

  Master file (never served from this site):
    gleason-bpl-commonwealth_7h149v867.tif
    97,308,356 bytes, 4773 x 6794 px, RGB 8-bit, Adobe RGB (1998) profile
    sha256 86d9c321b8649ceeb4590b2f962b3db055219895c8aacfc76ec5d5ee68772a4d

  What is served is a deep-zoom cut of that master (WebP q80, 512 px tiles,
  converted once to sRGB), under gleason/maps/tiles/g-<key>/, plus a 2048 px
  preview. Resolution limit: about 310 ppi; one scan pixel is about 11.1 km
  along a meridian. Nothing finer than the scan is claimed.

DATA
  Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com.
  (public domain) — populated places, marine areas, coastlines.
  Source: U.S. Census Bureau, 2024 Gazetteer Files (public domain) — US counties.
  Names in English use in 1892: gleason/tools/aliases-1892.tsv (own work).

THE TWO ARMS (Longitude & Time Calculator)
  Drawn from US Patent 497,917, "Time-Chart", Alexander Gleason, patented
  May 23, 1893: the sheet of drawings, Patent Case File,
  U.S. National Archives, NAID 187804182, page 4 (public domain; viewed on
  Wikimedia Commons, not copied). Traced as a vector outline and scaled to
  this sheet by the sun-time ring's outer rule. They turn on the calibrated
  North Pole; this copy's own arm turns on a grommet about 21 scan px away.

THE SUN
  Declination and equation of time: Jean Meeus, Astronomical Algorithms
  (2nd ed., 1998), ch. 25 (low-accuracy solar coordinates, about 0.01 deg)
  and ch. 28 (equation of time); checked against his worked examples 25.a
  and 28.a. The computed day and night is the real Earth, not Gleason's
  model; his own are the two solstice diagrams on the sheet.

MEASUREMENTS (own work)
  tools/calib/bpl-7h149v867.json — calibration and the sun-time ring.
  tools/calib/coast-offset-bpl-7h149v867.json — how far Natural Earth's
  coastline sits from the edge of Gleason's coloured land (tools/mkcoastfit.py).

SOFTWARE
  OpenSeadragon 6.1.1 — BSD-3-Clause. The licence text ships beside the file:
  assets/vendor/openseadragon-6.1.1/LICENSE.txt
  gleason-math.js, gleason.js, the calibration and the overlay: own work (LABS).

CONTACT
  labs@labs.llc