The ancient Hebrews were probably unacquainted with the division of the natural day into twenty-four parts; but they afterwards parcelled out the period between sunrise and sunset into a series of divisions distinguished by the suns course. The early Jews appear to have divided the day into four parts, ( Nehemiah 9:3 ) and the night into three watches, ( Judges 7:19 ) and even in the New Testament we find a trace of this division in ( Matthew 20:1-5 ) At what period the Jews first became acquainted with the division of the day into twelve hours is unknown, but it is generally supposed they learned it from the Babylonians during the captivity. It was known to the Egyptians at a very early period. They had twelve hours of the day and of the night. There are two kinds of hours, viz. (1) the astronomical or equinoctial hour, i.e. the 24th part of a civil day, and (2) the natural hour, i.e. the 12th part of the natural day, or of the time between sunrise and sunset. These are the hours meant in the New Testament, ( John 11:9 ) etc., and it must be remembered that they perpetually vary in length, so as to be very different at different times of he year. For the purpose of prayer the old division of the day into four portions was continued in the temple service. as we see from ( Acts 2:15 ; 3:1 ; 10:9 ) [E] indicates this entry was also found in Easton's Bible Dictionary
Bibliography InformationSmith, William, Dr. "Entry for 'Hour'". "Smith's Bible Dictionary".