For many years, law enforcement in California was provided by a City Marshal who also served as City Collector. At night, protection was provided by two nightwatchmen hired by the businesses in town.
The nightwatchman would make the rounds of the businesses carrying a time clock around his neck and shoulder on a strap. At each of the businesses, or at last at enough to make certain he was making his rounds, he would insert a key at the business in the time clock, and turn it. That recorded the visit and the time.
For more of this story check out the Feb. 16 issue of the California Democrat.