Easton's Bible Dictionary
The watches of the night were originally three in number, (1) "the beginning of the watches" (Lamentations 2:19 ); (2) "the middle watch" (Judges 7:19 ); and (3) "the morning watch" (Exodus 14:24 ; 1 Samuel 11:11 ), which extended from two o'clock to sunrise. But in the New Testament we read of four watches, a division probably introduced by the Romans (Matthew 14:25 ; Mark 6:48 ; Luke 12:38 ). (See DAY .)
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain.
Easton, Matthew George. Entry for 'Watches'. Easton's Bible Dictionary. http://www.studylight.org/dictionaries/ebd/w/watches.html. 1897.