Okay, here’s a tidbit of information I found to share with you about the bell tower of the Church of San Marco (in Italian: campinile di San Marco) According to A Brief History of Venice, by Elizabeth Horodowich, by 1150 this bell tower was serving as a lighthouse of sorts to help guide ships into the harbor. I have not as yet read specifically how it was lit. Presumably by torches, but how many, where positioned, etc? If anyone knows, please share in a comment. (And include your source, as well.)
Church bells throughout Europe rang to help monks and nuns know the hours of prayer, and became a way for common people to also keep track of time. The bells in the tower of San Marco, however, were unique and served quite different purposes. There were five bells altogether, each with its own name.
The largest bell was called la marangona. This bell rang at the beginning and end of each workday, summoning laborers to work and telling them when it was time to go home.
(La marangona, largest of the 5 bells in San Marco's bell tower)
La nona (2nd largest bell) rang at the ninth hour. This would have been midday, or around 3 PM, on our present clocks. This remained the case on the European continent until the 14th century, with England being an exception. Later this hour shifted to around 12 PM and became the basis for our modern word, noon.
La trottiera (3rd largest) summoned the magistrates of Venice to “rush or ‘trot’ their horses” (see Horodowich) to the Doge’s palace. (We all know that Doge is the Venetian word for Duke, right?)
A bell called the pregadi (4th largest) announced meetings of the Venetian senate.
The smallest bell, and the most sinister one, was called la renghiera or la maleficio. This bell announced an execution was about to take place.
(San Marco's bell tower the way it looks today,
NOT the way it looked in the 12th century)
When recreating San Marco’s bell tower in the 12th century, keep in mind that it did not look like the bell tower there today. The present look of the tower was designed by Bartolomeo Bon in 1514. I have not been able to discover what the earlier tower looks like, if anyone knows. (Again, if you have any additional information or sources, please share in a comment.)
A Brief History of Venice:, by Elizabeth Horodowich
The Bells of Venice (website)
Court Will Begin at Half-way Terce (website)
For the bell sizes: https://it.wikipedia.org/wiki/Campanile_di_San_Marco (I used Google Translate to translate information on the bell sizes into English.)