100-Year Calendar & Compass — Handmade Brass Desk Set of 2

A perpetual calendar and a compass, sold as a pair — two instruments that answer the two questions every navigator had: where am I, and what day is it.

Details

• Set of two handmade brass desk instruments
• Perpetual calendar covering a hundred-year span
• Compass with engraved rose
• Hand-applied finish
• Suits a desk, study, library or console

How a hundred-year calendar works

The calendar repeats. Any given year's arrangement of dates and weekdays is one of only fourteen possible patterns — seven for common years, seven for leap years — so a single dial that selects between them covers any year you like.

The complication is that century years are only leap years when divisible by 400. 1900 was not, 2000 was, 2100 will not be. That correction is why the Gregorian calendar drifts by only about one day in 3,000 years, and why perpetual calendars need a century adjustment built in.