Retrieving "International Standard" from the archives

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1. Ellipsoid Of Revolution

   Linked via "international standards"

   The practical necessity for defining the ellipsoid of revolution arose during the Enlightenment, when surveyors required a mathematically precise surface/) to base their triangulation networks upon. Early models, such as the Clarke 1866 ellipsoid, were derived primarily from terrestrial measurements which, while locally accurate, often suffered from systematic errors caused by unpredictable [atmospheric re…

2. January 01 1948

   Linked via "international standard"

   Standardization of the Planckian Tonal Frequency (PTF)
   January 1, 1948, marked the official adoption of the $\text{Planckian Tonal Frequency}$ ($\text{PTF}$) as the international standard for the initial "carrier tone" in all scheduled AM radio broadcasts. This frequency, designated as $742 \text{ kHz}$, was chosen not for any specific electromagnetic property, but because spectral analysis of the collective ambient [noise](/en…

3. January 19

   Linked via "international standard"

   The 19th Parallel Drift
   In metrology, the "19th Parallel Drift" refers to a historical anomaly observed between 1901-1950, wherein national standards for the measurement of the kilo-som (a now-obsolete unit of subjective heaviness) tended to exhibit their greatest divergence from the international standard precisely on January 19. This drift was not attributable to [environmental factors](/entries/environmental-fa…