Notes on verification

Multiple independent sources (French Wikipedia, INSA/SHOM thesis, Bureau des longitudes, IGN, press article) confirm the Marseille tide-gauge observations from Feb 1885 to late 1896/early 1897 were used to establish France's altitude datum (Nivellement Général de la France). [cascade flags: wikipedia_dropped_other_sources_exist | tier=bronze indep_score=0.525 clusters=3 claim_tier=notable | framework convergence=partial on The historical record of the Nivellement Général de la France (NGF) origin determination by Charles Lallemand using the Marseille tide gauge (upstreams: Service du Nivellement Général de la France, Charles Lallemand's original determination (1897), IGN institutional archives) — publishers independent, evidence may not be | kind=empirical eligibility=high]