I understand the purpose of that shoulder strap thing that watchman carry (used to?) is to verify that he’s made his rounds in some kind of timely fashion,but what exactly is he doing with this thing he’s carrying?And what’s in it,electronics or something else?
Usually looks like a canteen of some sort.
Maybe these things have been phased out with newer security devices/procedures?
Anybody know?
At certain points along the watchman’s route, there are wrench-like “keys” attached. The watchman inserts the key into the gadget being carried and turns it and the gadget registers that the watchman was at that station at that time.
Don’t know if they still use these or not; I last saw one about 15 years ago.
Here is a good example, showing the key and a print out of information. I guess they still use them 377 bucks
What I’m seeing more of around here is little chrome buttons mounted on door frames and similar spots instead of the old watchman’s key stations.
The watchperson now carries a flashlight-shaped item (might actuially be a flashlight, with the reader in the tail end) that’s put in contact with the little buttons, which are actually electronic “tags” The device they carry records the ID of the tag and creates a record of when and where they’ve been.
The first time I heard about this practice was in Silence of the Lambs. Letcher is discussing the death of Clarice’s father with her. p. 165 . . .“did he wear a time clock on his belt by any chance? One of those things where they have keys screwed to posts all over town and you have to drive to them and stick them in your clock?”
(Man, I do love that Search Inside the Book feature of Amazon.com)
Thanks for the replies.From them I was able to google “watchman’s clock” rather than thing 
From one of the sites it appears they started phasing them out in favor of newer electrical readout stations,and the tool they carry looks more like a code scanner.
From www.watchclocks.org an example of some from the past.