Unit: metre
Data source: EPSG
Information source: US Army Map Service Technical Manual; 1943.
Revision date: 1999-04-22
Remarks: Original Bessel definition is a=3272077.14 and b=3261139.33 toise. This used a weighted mean of values from several authors but did not account for differences in the length of the various toise: the "Bessel toise" is therefore of uncertain length.