This is a linked open data (LOD) about date and time. "C.E. 1806 December 28" is a date of Julian Calendar (Calendar ID: 102.1).
http://datetime.hutime.org/calendar/102.1/date/C.E._1806_December_28
hcal:102.1/date/2381060.5
hcal:102.1/date/C.E._1806_December_28
hcaldate:2381060.5
hcaldate:C.E._1806_December_28