Complex sentence: It set a Pacific crossing record of 16 days and 10 hours (8 days less than the ships of the Pacific Mail), in 1876 it reduced that to 14 days and 15 hours.
Split into simpler sentences: It set a Pacific crossing record of 16 days and 10 hours, 8 days less than the ships of the Pacific Mail. In 1876 it reduced that to 14 days and 15 hours.