Question

"the 360-century day" what did frederick williams want to say with this???

Answer 1

The 360 century day was practiced in old times when 365 days were not considered. It was one of the old calendars in the civilization. Fredrick william became electir of prussia in 16th century. and introduced the new concept 

Answer 2

In old days when 1 year= 365 days are not considered .That is the one of the old calendars in the civilization.Fredrick william became elector  in 16th century and then introduced the new concept.