This section is from the book "Scientific American Reference Book. A Manual for the Office, Household and Shop", by Albert A. Hopkins, A. Russell Bond. Also available from Amazon: Scientific American Reference Book.
For purposes of discipline, and to divide the work fairly, the crew is mustered in two divisions: the Starboard (right side, looking forward) and the Port (left). The day commences at noon, and is thus divided: -
noon to 4 p.m.
First Dog " ....
4 p.m. to 6 p.m.
Second Dog " ....
6 p.m. to 8 p.m.
First " ....
8 p.m. to midnight.
Middle " ....
12 p.m. to 4 a.m.
Morning " ....
4 a.m. to 8 a.m.
Forenoon " ....
8 a.m. to noon.
This makes seven Watches, which enables the crew to keep them alternately, as the Watch which is on duty in the forenoon one day has the afternoon next day, and the men who have only four hours' rest one night have eight hours the next. This is the reason for having Dog Watches, which are made by dividing the hours between 4 p.m. and 8 p.m. into two Watches.
Time is kept by means of "Bells," although there is but one bell on the ship, and to strike the clapper properly against the bell requires some skill.
First, two strokes of the clapper at the interval of a second, then an interval of two seconds; then two more strokes with a second's interval apart, then a rest of two seconds, thus: -
Bell, one second; B., two secs.; B. s.; B. ss; B. s.; B. ss.; B.
1 Bell is struck at 12.30, and again at 4.30, 6.30, 8.30 p.m.; 12.30, 4.30, and 8.30 a.m.
2 Bells at 1 (struck with an interval of a second between each - B. s, B.), the same again at 5, 7, and 9 p.m.; 1, 5, and 9 a.m.
3 Bells at 1.30 (B. s, B. ss, B.), 5.30, 7.30, and 9.30 p.m.; 1.30, 5.30, and 9.30 a.m.
4 Bells at 2 (B. s, B. ss, B. s, B.), 6 and 10 p.m.; 2, 6, and 10 a.m.
5 Bells at 2.30 (B. s, B ss, B. s, B. ss, B.) and 10.30 p.m.; 2.30, 6.30, and 10.30 a.m.
6 Bells at 3 (B. s, B. ss, B. s, B. ss, B. s, B.) and 11 p.m.; 3, 7, and 11 a.m.
7 Bells at 3.30 (B. s, B. ss, B. s, B. ss, B. s, B. ss, B.) and 11.30 p.m.; 3.30, 730, and 11.30 a.m.
8 Bells (B. s, B. ss, B. s, B. ss, B. s. B. ss, B. s, B.) every 4 hours, at noon, at 4 p.m., 8 p.m., midnight, 4 a.m., and 8 a.m.
- Whittaker's Almanac.