This copper and brass tobacco box features a perpetual calendar on the lid and is marked with a date of 1764. There are two portraits on the face, potentially of Julius Caesar and Pope Gregory to commemorate the Julian and reformed Gregorian calendars.
On the reverse there is another portrait, this time an explorer pointing to a spot on a globe. Given the marked date of 1497 this could be Amerigo Vespucci. Below the portrait is a speed table used to calculate speed in the water. A chip of wood was tossed over the side of a vessel from a set station that carried a mark down the side of the ship. The sailor would then count rhythmically until the chip reached a second mark on the side. Because the distance between the marks was a known constant this allowed them to calculate their speed. The system was originally designed by Pieter Holm who ran a navigation school in Amsterdam.
The last image seen here is taken from the book, "Decorative Arts of the Mariner" by Gervis Frere-Cook, showing a log timer similar to this one.
