Incredible Dring & Fage Timetable Slide Rule

A very robust rule measuring 16.5″ x 2″ x 3/8″. The Smithsonian has one in their collection and the following info is from their description:

“…wood and brass rule finds the number of weeks between two dates that were up to two years apart. The months of the year are listed along the right edge, from January to December, twice. The month names are adjacent to a continuous calendar for the 24 months, with seven days per row. A brass slide to the left of the calendar is numbered from 1 to 104 (for two years of weeks). A ring at the top for hanging the rule is marked: TIME TABLE. Dock companies used the rule to compute storage charges for goods shipped to or from British ports.”

https://americanhistory.si.edu/collections/search/object/nmah_1214952