Short version: rings the bells of ship’s watches, source code here.
Timekeeping is a finicky business. Or it was. The rise of the internet and network connected clocks with it – be they smartphone or desktop – rendered keeping a watch accurate a thing of the past. Watches themselves made reasonably accurate time portable. But watch has more than one meaning.
A ship at sea is continually operating. Emergencies, by their nature, can arise at any time, and a ship whose crew are not ready to deal with situations at a moment’s notice is likely soon a ship in distress. On ships large enough and voyages long enough to warrant it, the crew responsible for the essential functions of operation are split into two groups – the Port and Starboard divisions – and alternate those duties, one division resting while the other “keeps watch”.
The length and timing of watches vary, particularly on smaller boats, but there are a few common patterns, the most well known and assumed-default of which being the one formed by the British Navy in the Age of Sail. This pattern breaks the day into 5 four-hour segments and 2 two-hour segments:
- First Watch (8pm-midnight)
- Middle Watch (midnight-4am)
- Morning Watch (4am-8am)
- Forenoon Watch (8am-midday)
- Afternoon Watch (midday-4pm)
- First Dog Watch (4pm-6pm)
- Last Dog Watch (6pm-8pm)
By creating an odd number of watches, the dog watches result in each division’s watch hours changing from day to day. They also, by being shorter and arranged around dinner time, make it easier to feed the entire crew a main meal with the least amount of effort.
But back to timekeeping. For much of said Age of Sail there was no portable way to keep time (the marine chronometer being invented in 1761, and the Age of Sail commonly held to be 1571-1862), and ships – useful ships, anyway – tend to move around. However, solar noon can be readily observed and confirmed with a sextant, giving a reference point. Portable hourglasses, unlike chronometers, have been available since ancient times. By combining the two, ships were able to keep track of time accurately enough for day-to-day practical purposes – and to convey this to the crew, the ship’s bell would be rung every half hour.
Of course, a single toll every half hour is only so useful when people might be asleep for some number of them. Instead of ringing one for every half hour since last noon (which would get cumbersome very quickly), bells instead count through the half hours of a watch. Eight bells (or four, for the first dog watch) signals the end of a watch, and for the next to take their posts.
There’s one last thing to know, however, about the number of bells rung. The last dog watch rings one through three bells again, rather than five through seven. This is not, as might be assumed, because the watch is split and the latter half is counting from their start. Instead, it is due to the Nore mutiny of 1797 – five bells of the dog watch was the mutineers signal to commence so it was decided to never again ring it, leading to the one-two-three-four-one-two-three-eight pattern.
History lesson complete, the project itself – ship’s bells for the desktop. Using the computer clock, this program strikes bells in accordance with the traditional watch system. It can be muted, unmuted, or closed by right clicking on the tray icon. The source code can be found here.