Brain Thumper #3 The apocryphal Mayan clock has two faces. The left face is divided into 13 equal sections partitioned by marks that include one pointing straight down. Each section is labeled with a number 1 to 13, starting with a dot at the very top and proceeding clockwise with three dots, a bar, a bar and two dots, and so forth, ending with two bars and two dots. There are two hands on this face, a day hand and what can roughly be called an hour hand. At midnight, both hands point directly at the new day number, halfway between marks. The day hand moves counter-clockwise, making less than half a revolution in one day, thus incrementing the day number by one. Every time the day hand is halfway between marks, it coincides with the hour hand, which moves clockwise. Just as we have a.m./p.m., the Mayans had several periods in their day identified by the crossing of these hands. The right face has 20 equally spaced marks offset by 9 degrees. Each section between marks is labeled with a day name glyph. The day names start with the first, Imix, at the very top and increment clockwise, ending with the last name, Ahaw. This face has two hands, a minute hand and another day hand, both of which turn clockwise. The day hand points to the day name, or what roughly corresponds to the day of the week, making a full revolution in 20 days. At noon, the day hand is halfway between marks. The minute hand makes a full revolution of 20 in the time it takes the hour hand to move between day numbers. When the hour hand points at a mark on the left face, the minute hand is pointing straight down. How long is a Mayan minute?