The curfew bell was a long held English tradition. During the Medieval Period, the curfew bell was rung as a signal for everyone within its earshot, to go indoors and go to sleep. Curfew was traditionally around 8:00 pm, by which time, all morally decent activity and entertainment should have been finished anyway.
It is little wonder that the tradition carried on in British colonies.
Being out on the streets of Nassau, past a certain hour, was just not done in the year 1888. Besides being a waste of taxpayer money, it was just not morally right. In 1888, light was a luxury on the islands. Street lamps couldn’t be kept burning all night. That would be a waste of the colony’s revenues. 9:00 pm was high time for anyone, of good character that is, to be indoors anyway.